We have a study involving 5 different groups that each contain 9 participants (45 total). What two degrees of freedom would we report when we report the results of our study

Answers

Answer 1

Answer:

Degree of freedoms F(4,40)

Step-by-step explanation:

Given:

There is a study which is involving 5 different groups that each contains 9 participants (totally 45)

The objective is to calculate the degree of freedoms

Formula used:

Numerator degree of freedom = k-1

denominator degree of freedom=N-K

Solution:

Numerator degree of freedom = k-1

denominator degree of freedom=N-K

Where,

K= number of groups = 5

N= total number of observations

which is given as follows,

N=45

Then,

Numerator degree of freedom = k-1

=5-1

=4

Denominator degree of freedom = N-K

=45-5

=40

Therefore,

Degree of freedoms, F(4,40)


Related Questions

Question 2
A force F=5i+3j-2k is applied to move a block of cement from A(0,1,1) to B(4.-1,3).
Determine the work done by the force.

Answers

The work is simply the dot product of the force and displacement (which I assume are given in Newtons and meters, respectively):

W = F • d

W = (5i + 3j - 2k) N • ((4i - j + 3k) m - (j + k) m)

W = (5i + 3j - 2k) • (4i - 2j + 2k) Nm

W = (20 - 6 - 4) Nm

W = 10 J

is this right? PLEASE HELP ILL MARK

Answers

Answer:

yeah u r correct...

hope it helps ..stay safe healthy and happy.

The function c(r)=2r+12.5 represents the cost c, in dollars, of riding r rides
at a carnival. How much does it cost to get into the carnival? *
1 point
A.$2
B. $12.50
C. $14.50
D.r

Answers

so basically i think it is c or maybe b do inie meni myni mo

Children arrive at a house to do Halloween trick-or- treating according to a Poisson process at the unlucky rate of 13/hour. What is the probability that the time between the 15th and 16th arrivals will be more than 4 minutes ? (Hint: Think exponential.)
a) e e-2 = 0.1353
b) e-13/15 = 0.4204
c) e-1 = 0.3679
d) 1-2-1 = 0.6321

Answers

Answer:

0.4204 probability, option b.

Step-by-step explanation:

Exponential distribution:

The exponential probability distribution, with mean m, is described by the following equation:

[tex]f(x) = \mu e^{-\mu x}[/tex]

In which [tex]\mu = \frac{1}{m}[/tex] is the decay parameter.

The probability that x is lower or equal to a is given by:

[tex]P(X \leq x) = \int\limits^a_0 {f(x)} \, dx[/tex]

Which has the following solution:

[tex]P(X \leq x) = 1 - e^{-\mu x}[/tex]

The probability of finding a value higher than x is:

[tex]P(X > x) = 1 - P(X \leq x) = 1 - (1 - e^{-\mu x}) = e^{-\mu x}[/tex]

Children arrive at a house to do Halloween trick-or- treating according to a Poisson process at the unlucky rate of 13/hour

13 arrivals during an hour, which means that the mean time between arrivals, in minutes is of [tex]\mu = \frac{13}{60} = 0.2167[/tex]

What is the probability that the time between the 15th and 16th arrivals will be more than 4 minutes ?

This is P(X > 4). So

[tex]P(X > 4) = e^{-0.2167*4} = 0.4204[/tex]

So the correct answer is given by option b.

WILL GIVE BRAINLIEST!!!
Write as a polynomial: 14b + 1 - 6(2 - 11b)

Answers

Answer:

80b-11

Step-by-step explanation:

14b + 1 - 6(2 - 11b)

Distribute

14b+1-12+66b

Combine like terms

80b-11

Answer:

80b - 11

Step-by-step explanation:

what is the problem ?

just multiply it out and combine terms.

14b + 1 - 6(2 - 11b) = 14b + 1 - 12 + 66b = 80b - 11

Find the distance between the points (-5, -4) and (3, 1).

On a coordinate plane, points are at (3, 1), (negative 5, negative 4).

Answers

Step-by-step explanation:

it will help u

The solution of this equation has an error. Which of the following steps has the error? 18 − (3x + 5) = 8
Step 1: 18 − 3x + 5 = 8
Step 2: -3x + 23 = 8
Step 3: -3x = -15
Step 4: x = 5



Step 1 Step 2 Step 3 Step 4. ?

Answers

Answer:

Step 1

Because the number in front of the bracket is 1 and it is also affected by the negative sign(-),5 is supposed to be negative not positive because (negative by positive is negative)

And since the first step has an error in it,the remaining steps would also be wrong.

John's age 4 years ago, if he will be y years old in 5 years

Answers

9514 1404 393

Answer:

  y -9

Step-by-step explanation:

From 4 years ago until 5 years from now, John will age 9 years. That is, his age 4 years ago is 9 years less than it will be in 5 years.

John's age 4 years ago is y-9 years.

Find the value of x pls help

Answers

9514 1404 393

Answer:

  x = 36°

Step-by-step explanation:

The exterior angle is equal to the sum of the remote interior angles. A linear pair is supplementary. So, you can find x either of two ways:

  2x = x + (180 -4x)   ⇒   5x = 180   ⇒   x = 36

Or ..

  4x = x + (180 -2x)   ⇒   5x = 180   ⇒   x = 36

The value of x is 36°.

Identify the domain of the table of values shown

Answers

Answer:

{-6,0,2,4}

Step-by-step explanation:

need help now!!! Please and thanks ​

Answers

Answer:

the answer of r is 8 i hope it will help

Solve the system, or show that it has no solution. (If there is no solution, enter NO SOLUTION. If there are an infinite number of solutions, enter the general solution in terms of x, where x is any real number.)
20x − 80y = 100
−14x + 56y = −70
(x, y) =

Answers

Answer:

The system has an infinite set of solutions [tex](x,y) = (x, \frac{x-5}{4})[/tex]

Step-by-step explanation:

From the first equation:

[tex]20x - 80y = 100[/tex]

[tex]20x = 100 + 80y[/tex]

[tex]x = \frac{100 + 80y}{20}[/tex]

[tex]x = 5 + 4y[/tex]

Replacing on the second equation:

[tex]-14x + 56y = -70[/tex]

[tex]-14(5 + 4y) + 56y = -70[/tex]

[tex]-70 - 56y + 56y = -70[/tex]

[tex]0 = 0[/tex]

This means that the system has an infinite number of solutions, considering:

[tex]x = 5 + 4y[/tex]

[tex]4y = x - 5[/tex]

[tex]y = \frac{x - 5}{4}[/tex]

The system has an infinite set of solutions [tex](x,y) = (x, \frac{x-5}{4})[/tex]

In your office desk drawer you have 10 different flavors of fruit leather. How many distinct flavor groupings can you make with your fruit leather stash?​

Answers

100

You have 10 different flavors. Just multiply the ten with another ten.

the graph function f(x) is illustrated in figure below (-2,1) ,(-1,2) ,(1,2) ,(2,3) .Use the transformation techniques to graph the following functions

a) y=f(x)-2
b) y=f(-x)

Answers

Answer:

a) y = f(x) - 2 (x, y) ⇒ (x, y - 2)b) y = f(-x) (x, y) ⇒ (-x, y)

a) y=f(x)-2

(-2, 1) → (-2, 1 - 2) = (-2, -1)(-1, 2) → (-1, 2 - 2) = (-1, 0)(1, 2) → (1, 2 - 2) = (1, 0)(2, 3) → (2, 3 - 2) = (2, 1)

b) y=f(-x)

(-2, 1) → (-(-2), 1) = (2, 1)(-1, 2) → (-(-1), 2) = (1, 2)(1, 2) → (-1, 2)(2, 3) → (-2, 3)

Linda found that the cost to get a swimming pool installed in her backyard is a linear function of the pool's area. A swimming pool with an area of 1,000 square feet can be installed for $50,000, whereas the installation of an 800 square foot swimming pool costs $35,000. Select the correct graph that models the given relationship.

Answers

Answer:

$35,000

Step-by-step explanation:

if $50,000 is to install an area of 1,000 square feet swimming pool and $35,000 can be used to install an 800 square foot swimming pool I think the best graph model is 800 square feet for $35,000 for a cost cut of $15,000 is a good bargain

John runs a computer software store. Yesterday he counted 125 people who walked by the store, 58 of whom came into the store. Of the 58, only 21 bought something in the store. (Round your answers to two decimal places.)
(a) Estimate the probability that a person who walks by the store will enter the store.
(b) Estimate the probability that a person who walks into the store will buy something.
(c) Estimate the probability that a person who walks by the store will come in and buy something.
(d) Estimate the probability that a person who comes into the store will buy nothing.

Answers

Answer:

a) 0.46 = 46% probability that a person who walks by the store will enter the store.

b) 0.36 = 36% probability that a person who walks into the store will buy something.

c) 0.17 = 17% probability that a person who walks by the store will come in and buy something.

d) 0.64 = 64% probability that a person who comes into the store will buy nothing.

Step-by-step explanation:

A probability is the number of desired outcomes divided by the number of total outcomes.

(a) Estimate the probability that a person who walks by the store will enter the store.

58 out of 125. So

[tex]p = \frac{58}{125} = 0.46[/tex]

0.46 = 46% probability that a person who walks by the store will enter the store.

(b) Estimate the probability that a person who walks into the store will buy something.

58 walked, 21 bought. So

[tex]p = \frac{21}{58} = 0.36[/tex]

0.36 = 36% probability that a person who walks into the store will buy something.

(c) Estimate the probability that a person who walks by the store will come in and buy something.

21 came in and bought out of 125 that walked by. So

[tex]p = \frac{21}{125} = 0.17[/tex]

0.17 = 17% probability that a person who walks by the store will come in and buy something.

(d) Estimate the probability that a person who comes into the store will buy nothing.

0.36 probability that a person buys something, so 1 - 0.36 = 0.64 = 64% probability that a person who comes into the store will buy nothing.

A statistics professor plans classes so carefully that the lengths of her classes are uniformly distributed between 47.0 and 57.0 minutes. Find the probability that a given class period runs between 51.25 and 51.5 minutes.

Answers

Answer:

0.025 = 2.5% probability that a given class period runs between 51.25 and 51.5 minutes.

Step-by-step explanation:

Uniform probability distribution:

An uniform distribution has two bounds, a and b.

The probability of finding a value between c and d is:

[tex]P(c \leq X \leq d) = \frac{d - c}{b - a}[/tex]

Uniformly distributed between 47.0 and 57.0 minutes.

This means that [tex]a = 47, b = 57[/tex]

Find the probability that a given class period runs between 51.25 and 51.5 minutes.

[tex]P(c \leq X \leq d) = \frac{51.5 - 51.25}{57 - 47} = 0.025[/tex]

0.025 = 2.5% probability that a given class period runs between 51.25 and 51.5 minutes.

solve the inequality 4t^2 ≤ 9t-2 please show steps and interval notation. thank you!​

Answers

Answer:

[0.25, 2]

Step-by-step explanation:

We have

4t² ≤ 9t-2

subtract 9t-2 from both sides to make this a quadratic

4t²-9t+2 ≤ 0

To solve this, we can solve for 4t²-9t+2=0 and do some guess and check to find which values result in the function being less than 0.

4t²-9t+2=0

We can see that -8 and -1 add up to -9, the coefficient of t, and 4 (the coefficient of t²) and 2 multiply to 8, which is also equal to -8 * -1. Therefore, we can write this as

4t²-8t-t+2=0

4t(t-2)-1(t-2)=0

(4t-1)(t-2)=0

Our zeros are thus t=2 and t = 1/4. Using these zeros, we can set up three zones: t < 1/4, 1/4<t<2, and t>2. We can take one random value from each of these zones and see if it fits the criteria of

4t²-9t+2 ≤ 0

For t<1/4, we can plug in 0. 4(0)²-9(0) + 2 = 2 >0 , so this is not correct

For 1/4<t<2, we can plug 1 in. 4(1)²-9(1) +2 = -3 <0, so this is correct

For t > 2, we can plug 5 in. 4(5)²-9(5) + 2 = 57 > 0, so this is not correct.

Therefore, for 4t^2 ≤ 9t-2 , which can also be written as 4t²-9t+2 ≤ 0, when t is between 1/4 and 2, the inequality is correct. Furthermore, as the sides are equal when t= 1/4 and t=2, this can be written as [0.25, 2]

una fuerza constante F de magnitud igual a 3lb se aplica al bloque que se muestra en la figura. F tiene la misma dirección que el vector a= 3i + 4j. determine el trabajo realizado en la dirección de movimiento si el bloque se mueve de P1 (3, 1) a P2 (9, 3). Suponga que la distancia se mide en pies.

Answers

Uh is that Spanish? Bc I can’t speak Spanish

Please select the best answer from the choices provided

A
B
C
D

Answers

Answer:

C

Step-by-step explanation:

Answer: B

Step-by-step explanation:

In order to win a prize, Heather randomly draws two balls from a basket of 40. There are 25 blue balls, and the rest are green balls. Of the blue balls, 12% are winning balls. Of the green balls, 20% are winning balls. Calculate the expected number of winning balls that Heather draws.

Answers

Answer:

The expected number of winning balls that Heather draws is 0.3.

Step-by-step explanation:

The balls are chosen without replacement, which means that the hypergeometric distribution is used to solve this question.

Hypergeometric distribution:

The probability of x successes is given by the following formula:

[tex]P(X = x) = h(x,N,n,k) = \frac{C_{k,x}*C_{N-k,n-x}}{C_{N,n}}[/tex]

In which:

x is the number of successes.

N is the size of the population.

n is the size of the sample.

k is the total number of desired outcomes.

Combinations formula:

[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

Expected value of the hypergeometric distribution:

The expected value is given by:

[tex]E(X) = \frac{nk}{N}[/tex]

Expected number of blue and green balls:

40 balls, which means that [tex]N = 40[/tex]

2 are chosen, which means that [tex]n = 2[/tex]

25 are blue, which means that [tex]k = 25[/tex]

So

[tex]E(X) = \frac{nk}{N} = \frac{25(2)}{40} = 1.25[/tex]

1.25 balls are expected to be blue and 2 - 1.25 = 0.75 green.

Of the blue balls, 12% are winning.

Of the green balls, 20% are winning.

Calculate the expected number of winning balls that Heather draws.

[tex]E_w = 1.25*0.12 + 0.75*0.2 = 0.3[/tex]

The expected number of winning balls that Heather draws is 0.3.

1) What is the opposite of adding 5?
2) What is the opposite of subtracting 20?
3) What is the opposite of multiplying by 1/2?
4) What is the opposite of dividing by 10?

Answers

Answer:

1) subtracting 5

2) adding 20

3) dividing by 2 (multiplying by 1/2)

4) multiplying by 1/10 (dividing by 10)

Step-by-step explanation:

There are four main operations in math: adding, subtracting, multiplying, and dividing. Each of the operations has an opposite. Adding and subtracting are opposites and multiplying and dividing are opposites. This means that subtracting can undo adding and vice versa; additionally, dividing can undo multiplying or vice versa. So, to find the opposite of something switch the operation to the opposite and keep the number. However, it is important to note that with multiplying and dividing you can also find the opposite by keeping the operation while changing the number to the reciprocal.

There are 92 students enrolled in an French course and 248 students enrolled in a Spanish course. Construct a ratio comparing students enrolled in a French course to students enrolled in a Spanish course. Write your answer as a decimal, rounded to the thousandths place.

Answers

Answer:

0.371

Step-by-step explanation:

The ratio comparing students enrolled in a French course to students enrolled in a Spanish course rounded to the thousandths place is 0.371.

What is the ratio?

A ratio indicates how many times one number contains another. If a and b are to objects then ratio of a to the b is given as a : b.

Now it is given that,

Students enrolled in a French course = 92

Students enrolled in a Spanish course = 248

So, Ratio comparing students enrolled in a French course to students enrolled in a Spanish = Students enrolled in a French course / Students enrolled in a Spanish course

Ratio comparing students enrolled in a French course to students enrolled in a Spanish = 92/248

Ratio comparing students enrolled in a French course to students enrolled in a Spanish = 0.370967

To rounded to the thousandths place, the digit at the thousandth place is 0 and right to it is 9 which is greater than 5 so round up the place value at thousandths place.

Ratio comparing students enrolled in a French course to students enrolled in a Spanish = 0.371

Thus, the ratio comparing students enrolled in a French course to students enrolled in a Spanish course rounded to the thousandths place is 0.371.

To learn more about ratio:

https://brainly.com/question/1504221

#SPJ2

CAN SOMEONE HELP ME ON ANALYZING DOT PLOTS!!!

Answers

Answer:

yes

Step-by-step explanation:

but I can't see them here

In 2013, the Public Religion Research Institute conducted a survey of 1,033 adults, 18 years of age or older, in the continental United States. One of the questions on their survey was as follows:

Answers

Answer:

Probability[Number of people from church] = 0.26 (Approx.)

Step-by-step explanation:

Given:

Total number of adult in survey = 1,033

Missing information:

Number of people from church = 269

Find:

Probability[Number of people from church]

Computation:

Probability of an event = Number of favourable outcomes / Number of total outcomes

Probability[Number of people from church] = Number of people from church / Total number of adult in survey

Probability[Number of people from church] = 269 / 1,033

Probability[Number of people from church] = 0.2604

Probability[Number of people from church] = 0.26 (Approx.)

Which choice correctly shows the line y = -x?
А
B
NOW
-
1 2 3 4
NH
-4 -3 -2 -1 1 2 3 4
UN
С
2
1 2 3 4
-4-3-2/4 1 2 3 4
-4 -3 -2 -3
NA
2
At
2

Answers

Answer:

The answer is A

Step-by-step explanation:

Hope this helps

Find the Taylor series for f(x) centered at the given value of a. (Assume that f has a power series expansion. Do not show that Rn(x)→0 . f(x)=lnx, a=

Answers

Answer:

Here we just want to find the Taylor series for f(x) = ln(x), centered at the value of a (which we do not know).

Remember that the general Taylor expansion is:

[tex]f(x) = f(a) + f'(a)*(x - a) + \frac{1}{2!}*f''(a)(x -a)^2 + ...[/tex]

for our function we have:

f'(x) =  1/x

f''(x) = -1/x^2

f'''(x) =  (1/2)*(1/x^3)

this is enough, now just let's write the series:

[tex]f(x) = ln(a) + \frac{1}{a} *(x - a) - \frac{1}{2!} *\frac{1}{a^2} *(x - a)^2 + \frac{1}{3!} *\frac{1}{2*a^3} *(x - a)^3 + ....[/tex]

This is the Taylor series to 3rd degree, you just need to change the value of a for the required value.

A Professor at a Nigerian University sent his phone number in a disorderly manner to his students. The disordered phone number was 82002273285.To know his real phone number, he gave the student the following conditions:(1) Eight (8) must come between two zeros (0's). (2)The first number after the first condition is met must not be an odd number and it must be greater than 5. (3)The seventh number must be 1. (4) The fifth and sixth numbers must be two numbers whose difference is 1 and the bigger number must come first.(5)The fifth and sixth numbers are greater than 2.(6)The ninth and tenth numbers are the same.(7)The eighth number is greater than the last number (8) The phone number must be 11 digits. What is the Professor's real phone number? ​

Answers

Answer:

I think you have a type.. "the seventh number must be a 1"

there are no 1's in the original set of numbers

Step-by-step explanation:





Which expression has a value of 15 when it equals
2
49-57
3--5
61-28
28
19

Answers

Answer:

it is 61-28 but I not sure u can scan for any application to make sure u get it ur answer thx for

2/9 divided by 5/6
help pleaseee​

Answers

Hey there!

[tex]\mathsf{\dfrac{2}{9}\div\dfrac{5}{6}}[/tex]

[tex]\mathsf{= \dfrac{2\times6}{9\times5}}[/tex]

[tex]\mathsf{2\times 6 = \bf 12}[/tex]

[tex]\mathsf{9\times5 = \bf 45}[/tex]

[tex]\boxed{\mathsf{=\bf \dfrac{12}{45}}}[/tex]

[tex]\large\textsf{BOTH NUMBERS has the Greatest Common Factor (GCF) of 3}[/tex]

[tex]\mathsf{= \dfrac{12\div3}{45\div3}}[/tex]

[tex]\mathsf{12\div3=\bf 4}[/tex]

[tex]\mathsf{45\div3=\bf 15}[/tex]

[tex]\boxed{\mathsf{=\bf \dfrac{4}{15}}}[/tex]

[tex]\boxed{\boxed{\large\textsf{Answer: }\mathsf{\bf \dfrac{4}{15}}}}\huge\checkmark[/tex]

[tex]\large\textsf{Good luck on your assignment and enjoy your day!}\\\\\\~\frak{Amphitrite1040:)}}[/tex]

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How did technological advancements change manufacturing methods duringthe Industrial Revolution? why is human development index necessary? A uniform 1500-kg beam, 20.0 m long, supports a 15,000-kg printing press5.0 m from the right support column (Figure slide 8). Calculate the forceon each of the vertical support columns. Paul, the Director of Recruitment at an insurance company, finds that the company has a disparate impact on the proportion of Hispanic employees compared to the proportion of Hispanics in the labor market. Which of the following steps should Paul take to solve the problem most efficiently? a) He should lower the job specifications for Hispanic applicants. b) He should continue using the current recruiting practices because only organizations with affirmative action plans are required to meet EEO guidelines. c) He should start advertising for job openings on the local Spanish radio station. d) He should freeze the hiring process until qualified Hispanics apply for vacant positions Factor using the perfect squares method:x^2 - 3x + 16 Lennies death is paralleled bySelect one:a. the death of the puppyb. the death of Candys dogc. the death of Curleys wifed. All of the above A public opinion survey is administered to determine how different age groups feel about an increase in the minimum wage. Some of the results are shown in the table below. For Against No Opinion 21-40 years 20 541-60 years 20 20 Over 60 years 55 15 5The survey showed that 40% of the 21 - 40 year-olds surveyed are against an increase, and 15% of the entire sample surveyed has no opinion. How many 21 - 40 year-olds surveyed are for an increase? How many 41 - 60 year-olds are against an increase? if TS is a midsegment of PQR find TS The quantity demanded of cereal increased from 1,350 to 1,700 when the price of milk decreased from $2.05 to $1.65. What is the estimated cross-price elasticity of demand for cereal Redbud Company uses a certain part in its manufacturing process that it buys from an outside supplier for $44 per part plus another $6 for shipping and other purchasing-related costs. The company will need 10,000 of these parts in the next year and is considering making the part internally. After performing a capacity analysis, Redbud determined that it has sufficient unused capacity to manufacture the 10,000 parts but would need to hire a manager at an annual salary of $40,000 to oversee this production activity. Estimated production costs are determined to be:Direct material $ 28 Direct labor 12 Variable overhead 6 Fixed overhead (includes manager at $4 per unit) 10 Total unit cost $ 56A) Identify the relevant costs to make this part internally. (Select all that apply)A) Historical cost B) Direct labor C) Direct material D) Variable overhead E) Fixed overhead F) New manager's salaryB) Should Redbud produce the part or continue to buy it from the outside supplier? (Select the right answer)A) Redbud should produce the part. B) Redbud is indifferent about the decision. C) Redbud should continue to buy it from the outside supplier.C.What are the other factors that Redbud Company should consider in deciding to make the part internally? (Select all that apply.)A) Total sales quantity.B) The potential for improved control over the availability of the parts by having it when needed and the potential for improved quality of the parts.C) Since Redbud Company is considering the use of currently available capacity, it should evaluate any relevant opportunity costs of using this capacity for more profitable activities. Which of the following graphs represents the equation y-2 = 3(x - 1)? What is the measure of angle b The volume of a right circular cylinder can be approximated as follows: Volume = ?r2h; where r is the radius of the cylinder and h is the height of the cylinder; ? is a constant that is roughly equal to 3. Using the simple approximation above, calculate the volume of a right circular cylinder with a radius of 2 meters and a height of 9 meters In addition to highly repeated DNA sequences and unique (single-copy) DNA sequences, a third class of DNA exists. What is it called, and what types of elements are involved in it A car took 5 minutes to travel from town A to town B which are 12km apart.Calculate the average speed of the path. find the 9th and 15th terms of the following geometric sequence 2, -4, 8, -16 QuestionPrice of Book $14.99 9.99Copies Sold at That Price 100,000 174.000Total Revenue at That Price 1,499,000 1,738,000Based on the data in the table and using the midpoint formula, between a price of $9.99 and $14.99, the price elasticity of demand for books isA) -0.74.B) -1.16.C) -1.35.D) -14.8. Please helpPlease answer correctly Piaget's nursemaid told his family that she saved his life from an attempted kidnapping. Piaget believed the nursemaid and later recalled details of the event, even though it never actually took place. Piaget's ability to recall an event that never took place is demonstrative of: chemistry definition of