Answer:
0.2061 = 20.61% probability, given a class size of 30 students, the average time to complete the test is less than 48.5 minutes
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal Probability Distribution
Problems of normal distributions can be solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
Mean of 50 minutes and a standard deviation of 10 minutes.
This means that [tex]\mu = 50, \sigma = 10[/tex]
Class size of 30 students
This means that [tex]n = 30, s = \frac{10}{\sqrt{30}}[/tex]
What is the probability, given a class size of 30 students, the average time to complete the test is less than 48.5 minutes.
This is the p-value of Z when X = 48.5. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
By the Central Limit Theorem
[tex]Z = \frac{X - \mu}{s}[/tex]
[tex]Z = \frac{48.5 - 50}{\frac{10}{\sqrt{30}}}[/tex]
[tex]Z = -0.82[/tex]
[tex]Z = -0.82[/tex] has a p-value of 0.2061
0.2061 = 20.61% probability, given a class size of 30 students, the average time to complete the test is less than 48.5 minutes
There is enough grass to feed six cows for three days. How long would the same amount of grass feed nine cows
Answer:
2 days
Step-by-step explanation:
Lets say that in one day, one cow eats 1 block of grass. So, six cows in three days would eat 18 blocks of grass in total. So 18 blocks of grass is how much we have. that means nine cows would eat that much in 2 days.
In the coordinate plane, two vertices of square ABCD are A (0,0) and B (0, m). What are the coordinates of points C and D? Do not introduce any new variables.
Answer:
Step-by-step explanation:
As shown in the graph,
A, B, C and D are the vertices of a square, all sides of the square will be equal in measure.
Coordinates of A → (0, 0)
Coordinates of B → (0, m)
Distance between point D and point A = m
Therefore, coordinates of point D → (m, 0)
Now point C will be equally distant from the points B and D.
Coordinates of C → (m, m)
The following data were obtained from 4 people Pre-Test Value Post-test Value 43 42 28 29 31 30 28 25 You may also assume that the sample standard deviation for the four differences is 1.6. What is the correct t-statistic and the degrees of freedom for these data
Answer:
Test statistic = 1.25
Degree of freedom = 3
Step-by-step explanation:
The following data were obtained from 4 people
Pre-Test Value Post-test Value __ d
43 ________42 _________ 1
28_______ 29 ________ - 1
31 ________30 _________ 1
28 ________ 25 _________ 3
μd = (1 + - 1 + 1 + 3) / 4 = 4 /4 = 1
The mean difference, μd = 1
The standard deviation of difference, Sd = 1.6
The test statistic = μd / (Sd / √n)
Test statistic = 1 / (1.6/2) = 1 / 0.8
Test statistic = 1.25
Degree of freedom, = n - 1 = 4 - 1 = 3
A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of is _____. an. approximately normal because is always approximately normally distributed b. approximately normal because the sample size is large in comparison to the population size c. approximately normal because of the central limit theorem d. normal if the population is normally distributed
Answer:
d. normal if the population is normally distributed
Step-by-step explanation:
Central Limit Theorem
The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this question:
Sample size less than 30, so only will be normal if the population is normally distribution, and thus the correct answer is given by option d.
Solve the simultaneous equations
6
x
+
2
y
=
12
5
x
+
2
y
=
8
Answer: x=4, y=-6
Step-by-step explanation:
Work out the surface area of this sphere.
Give your answer to 1 decimal place.
Spheres
Surface area =
4tr?
6 cm
Answer:
452.2 cm
Step-by-step explanation:
A = 4πr²
A = 4 (3.14) (6)²
A = 4 (3.14) (36)
A = 452.16
A = 452.2 cm (nearest tenth)
The polynomial 3x² + mx? - nx - 10 has a factor of (x - 1). When divided by x + 2, the remainder is 36. What are
the values of m and n?
Answer:
[tex]m = 12[/tex]
[tex]n =3[/tex]
Step-by-step explanation:
Given
[tex]P(x) = x^3 + mx^2 - nx - 10[/tex]
Required
The values of m and n
For x - 1;
we have:
[tex]x - 1 = 0[/tex]
[tex]x=1[/tex]
So:
[tex]P(1) = (1)^3 + m*(1)^2 - n*(1) - 10[/tex]
[tex]P(1) = 1 + m*1 - n*1 - 10[/tex]
[tex]P(1) = 1 + m - n - 10[/tex]
Collect like terms
[tex]P(1) = m - n + 1 - 10[/tex]
[tex]P(1) = m - n -9[/tex]
Because x - 1 divides the polynomial, then P(1) = 0;
So, we have:
[tex]m - n -9 = 0[/tex]
Add 9 to both sides
[tex]m - n = 9[/tex] --- (1)
For x + 2;
we have:
[tex]x + 2 = 0[/tex]
[tex]x = -2[/tex]
So:
[tex]P(-2) = (-2)^3 + m*(-2)^2 - n*(-2) - 10[/tex]
[tex]P(-2) = -8 + 4m + 2n - 10[/tex]
Collect like terms
[tex]P(-2) = 4m + 2n - 10 - 8[/tex]
[tex]P(-2) = 4m + 2n - 18[/tex]
x + 2 leaves a remainder of 36, means that P(-2) = 36;
So, we have:
[tex]4m + 2n - 18 = 36[/tex]
Collect like terms
[tex]4m + 2n = 36+18[/tex]
[tex]4m + 2n = 54[/tex]
Divide through by 2
[tex]2m + n=27[/tex] --- (2)
Add (1) and (2)
[tex]m + 2m - n + n = 9 +27[/tex]
[tex]3m =36[/tex]
Divide by 3
[tex]m = 12[/tex]
Substitute [tex]m = 12[/tex] in (1)
[tex]m - n =9[/tex]
Make n the subject
[tex]n = m - 9[/tex]
[tex]n = 12 - 9[/tex]
[tex]n =3[/tex]
The expression x−y equals 0.7 if x and y have certain values. Evaluate the following expressions with the same values of x and y. What is 1/x-y.
PLEASE HELP FAST I NEED THIS DONE IN 30 MINUTES!!!
Answer:
10/7 or 1.428571429
Step-by-step explanation:
We know that x-y=0.7
So, now we have the equation 1÷0.7 or 1÷7/10
Meaning, we can multiply by the reciprocal,
And make this equation into 1×10/7= 10/7
Which of these figures has rotational symmetry?
Hello!
The answer is a.
Good luck! :)
Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar(s). Consider the equation below. The value of x in terms of b is . The value of x when b is 3 is .
Answer: x=-3/3=-1
Step-by-step explanation:
To solve for x in terms of b, simply treat b as a number, and solve for x as usual: first of all, we expand the left hand side:
-2bx+10=16
Subtract 10 from both sides:
-2bx=6
Divide both sides by -2b:
x=6/-2b=-3/b
This means that in particular, if we set b=3 , we have
x=-3/3=-1
A university found that 25% of its students withdraw without completing the introductory statistics course. Assume that 30 students registered for the course.Use Microsoft Excel whenever necessary and answer the following questions:Compute the probability that 2 or fewer will withdraw
Answer:
0.0106 = 1.06% probability that 2 or fewer will withdraw
Step-by-step explanation:
For each student, there are only two possible outcomes. Either they withdraw, or they do not. The probability of an student withdrawing is independent of any other student, which means that the binomial probability distribution is used to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
In which [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]
And p is the probability of X happening.
25% of its students withdraw without completing the introductory statistics course.
This means that [tex]p = 0.25[/tex]
Assume that 30 students registered for the course.
This means that [tex]n = 30[/tex]
Compute the probability that 2 or fewer will withdraw:
This is:
[tex]P(X \leq 2) = P(X = 0) + P(X = 1) + P(X = 2)[/tex]
In which
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
[tex]P(X = 0) = C_{30,0}.(0.25)^{0}.(0.75)^{30} = 0.0002[/tex]
[tex]P(X = 1) = C_{30,1}.(0.25)^{1}.(0.75)^{29} = 0.0018[/tex]
[tex]P(X = 2) = C_{30,2}.(0.25)^{2}.(0.75)^{28} = 0.0086[/tex]
[tex]P(X \leq 2) = P(X = 0) + P(X = 1) + P(X = 2) = 0.0002 + 0.0018 + 0.0086 = 0.0106[/tex]
0.0106 = 1.06% probability that 2 or fewer will withdraw
Sam thinks of a 4 digit number. The digit in the one’s place is 3 less than the digit in the ten’s place and digit in thousand’s place is 5 less than the digit in hundred’s place. The value of the hundred’s place is 800. The digit in ten’s place is the greatest even number. What is the number Sam is thinking of?
9514 1404 393
Answer:
3885
Step-by-step explanation:
The hundreds digit is 8, and the thousands digit is 5 less, so is 3.
The tens digit is 8 (the largest even digit), and the ones digit is 3 less, so is 5.
The number is ...
3885
Determine the mean and variance of the random variable with the following probability mass function. f(x)=(216/43)(1/6)x, x=1,2,3 Round your answers to three decimal places (e.g. 98.765).
Mean:
E[X] = ∑ x f(x) = 1 × f (1) + 2 × f (2) + 3 × f (3) = 51/43 ≈ 1.186
Variance:
Recall that for a random variable X, its variance is defined as
Var[X] = E[(X - E[X])²] = E[X ²] - E[X]²
Now,
E[X ²] = ∑ x ² f(x) = 1² × f (1) + 2² × f (2) + 3² × f (3) = 69/43
Then
Var[X] = 69/43 - (51/43)² = 366/1849 ≈ 0.198
(each sum is taken over x in the set {1, 2, 3})
Pls solve the above question
Kindly don't spam+_+
Answer:
Step-by-step explanation:
Given expressions are,
[tex]p=\frac{\sqrt{10}-\sqrt{5}}{\sqrt{10}+\sqrt{5}}[/tex] and [tex]q=\frac{\sqrt{10}+\sqrt{5}}{\sqrt{10}-\sqrt{5}}[/tex]
Remove the radicals from the denominator from both the expressions.
[tex]p=\frac{\sqrt{10}-\sqrt{5}}{\sqrt{10}+\sqrt{5}} \times \frac{\sqrt{10}-\sqrt{5}}{\sqrt{10}-\sqrt{5}}[/tex]
[tex]=\frac{(\sqrt{10}-\sqrt{5})^2}{(\sqrt{10})^2-(\sqrt{5})^2}[/tex]
[tex]=\frac{(\sqrt{10}-\sqrt{5})^2}{5}[/tex]
[tex]\sqrt{p}=\sqrt{\frac{(\sqrt{10}-\sqrt{5})^2}{5}}[/tex]
[tex]=\frac{\sqrt{10}-\sqrt{5}}{\sqrt{5}}[/tex]
[tex]q=\frac{\sqrt{10}+\sqrt{5}}{\sqrt{10}-\sqrt{5}}[/tex]
[tex]=\frac{\sqrt{10}+\sqrt{5}}{\sqrt{10}-\sqrt{5}}\times \frac{\sqrt{10}+\sqrt{5}}{\sqrt{10}+\sqrt{5}}[/tex]
[tex]=\frac{(\sqrt{10}+\sqrt{5})^2}{(\sqrt{10})^2-(\sqrt{5})^2}[/tex]
[tex]=\frac{(\sqrt{10}+\sqrt{5})^2}{5}[/tex]
[tex]\sqrt{q}=\sqrt{\frac{(\sqrt{10}+\sqrt{5})^2}{5}}[/tex]
[tex]=\frac{(\sqrt{10}+\sqrt{5})}{\sqrt{5}}[/tex]
[tex]\sqrt{q}-\sqrt{p}-2\sqrt{pq}=\frac{(\sqrt{10}+\sqrt{5})}{\sqrt{5}}-\frac{(\sqrt{10}-\sqrt{5})}{\sqrt{5}}-2(\frac{(\sqrt{10}+\sqrt{5})}{\sqrt{5}})(\frac{(\sqrt{10}-\sqrt{5})}{\sqrt{5}})[/tex]
[tex]=\frac{1}{\sqrt{5}}(\sqrt{10}+\sqrt{5}-\sqrt{10}+\sqrt{5})-\frac{2}{5}[(\sqrt{10})^2-(\sqrt{5})^2)][/tex]
[tex]=\frac{1}{\sqrt{5}}(2\sqrt{5})-\frac{2}{5}(10-5)[/tex]
[tex]=2-2[/tex]
[tex]=0[/tex]
Which parabola opens upward?
y = 2x – 4x^2 – 5
y = 4 – 2x^2 –5x
y = 2 + 4x – 5x^2
y = –5x + 4x^2 + 2
Answer:
D) y = –5x + 4x^2 + 2
Step-by-step explanation:
You can tell by the first number being positive or negative. To check use Desmo graphing calculator and enter your equation for next time.
Solve 7 pleaseeeeeeeeeeeeeeeee
Answer:
5040
Step-by-step explanation:
I assume you really mean 7!
you understand what "!" means ?
n! = n×(n-1)×(n-2)×(n-3)×...×3×2×1
so,
7! = 7×6×5×4×3×2×1
now all you need is a calculator.
7! = 5040
A mechanic charges $65 for an engine check and $20 per hour for his
services. Which of the following is a linear model of his charges.
y=20x+65
y=65x+20
y=3.25x+65
O y=3.25x+20
Question 5
Answer:
y = 65 + 20x
Step-by-step explanation:
Okay, when you're talking about linear equations try to find the fixed value, and then the changing one.
The fixed value will be by itself
The value that varies will have a variable next to it (x, y, z, whatever)
Then, the answer has to be
y = 65 + 20x
Please help it’s kinda confusing only got 20 minutes left !!
For a confidence level of 88%, find the critical value for a normally distributed variable. The sample mean is normally distributed if the population standard deviation is known.
Answer:
z = ± 0.772193214
Step-by-step explanation:
Hence, the critical value for a [tex]88[/tex]% confidence level is [tex]z=1.56[/tex].
What is the standard deviation?
Standard deviation is the degree of dispersion or the scatter of the data points relative to its mean, in descriptive statistics.
It tells how the values are spread across the data sample and it is the measure of the variation of the data points from the mean.
Here given that,
For a confidence level of [tex]88[/tex]%, find the critical value for a normally distributed variable.
Let us assume that the standard normal distribution having a mean is [tex]0[/tex] and the standard deviation is [tex]1[/tex].
As the significance level is [tex]1[/tex] - confidence interval
Confidence interval is [tex]\frac{80}{100}=0.88[/tex]
i.e., [tex]1-0.88=0.12[/tex]
For the two sided confidence interval the confidence level is [tex]0.44[/tex].
Now, the standard normal probability table the critical value for the [tex]88[/tex]% confidence level is [tex]1.56[/tex].
Hence, the critical value for a [tex]88[/tex]% confidence level is [tex]z=1.56[/tex].
To know more about the standard deviation
https://brainly.com/question/13905583
#SPJ5
PLEASE HELP!!! Which number is a solution of the inequality x less-than negative 4? Use the number line to help answer the question. A number line going from negative 9 to positive 1.
Answer:
is it going to be 10.5
Step-by-step explanation:
I do not have any explanation
Answer: 0 (zero)
Step-by-step explanation:
Start Learning & start growing! edge2023
*DROPS THE MIC*
We want to know if money affects happiness. We surveyed 20 people one week before they were notified of winning a large publishers clearing house sweepstakes and then again one month after they recieved their prize. What test would we use to compare their previous scores with their current scores
Answer:
Dependent Samples t test
Step-by-step explanation:
The dependent samples t test also called the paired t test are employed in statistical analysis when sample measurement in a certain group is to be paired with the sample measurement on the other group. This is possible because the samples used in the two groups are usually the same. Hence, pairing the samples is feasible in this case. This is different from independent t test as the samples in the groups are entirely different and distinct. Hence, giving no chance to match the samples together. In the scenario described above, the same 20 people(samples) formed the same group of measurement.
rotation 90 degrees counterclockwise about the origin
I'm going to try my best to explain 90° rotation:
So, you know that if you rotate something 180°, it's completely flipped (think about spinning around half-way).
Or if you spin something 360°, you spin around the whole way and end up in the same spot that you did when you started.
Notice how 90 is actually 1/4 of 360.
So imagine spinning instead of 180, spinning half of that. so you barely rotate. That's exactly what you're doing to this shape here. and if you do it about the origin counterclockwise, the origin is (0,0) so I drew it in Quadrant III, as you can see in my attachment.
You can see that every point has been moved by 90°, I put all of the variables there so you could visualize it better!
I hope this helped, let me know if you have any questions! :)
Greatest to least 2,250 2,700 2,450 2,500
Answer:
sorting;
2,7002,5002,450 2,250greatest = 2,700
least = 2,250
HAVE A NİCE DAY
Step-by-step explanation:
GREETINGS FROM TURKEY ツ
giving brainiest Elinor solved this problem. Is her answer correct?
8.93 times 0.15 = 4465. 4465 + 8930 = 13.395
No, Elinor should have placed the decimal point between the 1 and the 3.
No, she should have placed the decimal point between the 3 and the 9.
No, she did not align the place values in the partial products correctly.
Yes. Elinor did not make an error. giving Branniest
Answer:
its a
Step-by-step explanation:
trust did test
HW HELP ASAP PLZZZZZ
Answer:
p = 15/x
x= -3
Step-by-step explanation:
For the first problem, we can expand the equation to 4px+4=64
then simplify it to:
4px=60
then divide 4x from both sides of the equation
p=60/4x
then simplify:
p=15/x
For the second problem:
plug in -5 for p so the equation would look like
4(-5x +1)=64
simplify
-20x=60
x= -3
Roulette is a casino game that involves spinning a ball on a wheel that is marked with numbered squares that are red, black, or green. Half of the numbers 1 - 36 are colored red and half are black and the numbers 0 and 00 are green. Each number occurs only once on the wheel. What is the probability of landing on an even number and a number greater than 17? (A number is even if it is divisible by 2. 0 and 00 are considered even as well.)
Answer:
the wording (punctuation) of the question can lead to different interpretations....
I assume that the question was >17 & even which is "5/19",
BUT... it can also be read as two questions
first >17 which is "10/19"
and second an even number which is "9/19"
BUT !!! I think that the question answer is 5/19
Step-by-step explanation:
Even Number = 18/38 = 9/19
greater 17 = 20/38 = 10/19
Even & greater 17 = 10/38 = 5/19
what is the answer to 10% of 900
Answer:
90 cause 90 times 10 is 900 and 10% times 10 is 100%
Step-by-step explanation:
Answer: 90
Step-by-step explanation: 900 × .10 = 90
HELP ASAP PLS Select the correct answer.
A light bulb's brightness is reduced when placed behind a screen. The amount of visible light produced by the light bulb decreases by 25% with
each additional layer that is added to the screen. With no screen, the light bulb produces 750 lumens. The lumen is a unit for measuring the total
quantity of visible light emitted by a source,
Select the correct equation that can be used to represent the lumens, L, after x screen layers are added.
Answer:
D. 750(0.75)ˣ
Step-by-step explanation:
Let the new brightness be L'. Since our initial brightness L₀ reduces by 25 %, we have that L' = L₀ - 25% of L₀
L' = L₀ - 0.25L₀
L' = 0.75L₀
Adding the second screen, the new intensity is L" = L' - 25 % of L'
L" = L' - 0.25 L'
L" = 0.75L'.
Since L' = 0.75L₀,
L" = 0.75L' = 0.75(0.75L₀) = 0.75²L₀
Adding the third screen, the new intensity is L"' = L'' - 25 % of L''
L'" = L" - 0.25 L"
L"' = 0.75L".
Since L" = 0.75L' = 0.75²L₀
L"' = 0.75L" = 0.75(0.75²L₀) = 0.75³L₀
So, we see a pattern here.
The intensity after x screens is L = (0.75)ˣL₀
Since L₀ = 750 lumens,
L = 750(0.75)ˣ
Please help me in this question
Answer:
3/8
Step-by-step explanation:
the total number of possible results is 4×4=16.
out of these 16 only the results
1 2
1 3
1 4
2 2
2 3
3 2
are desired results. these are 6.
so the probability of a desired result is 6/16 = 3/8
A full glass of water can hold 1/6 of a bottle.
How many glasses of water can be filled with 3 bottles of water
