Answer:
x = -5 or x = i sqrt(3) or x = -i sqrt(3)
Step-by-step explanation:
Solve for x:
x^3 + 5 x^2 + 3 x + 15 = 0
The left hand side factors into a product with two terms:
(x + 5) (x^2 + 3) = 0
Split into two equations:
x + 5 = 0 or x^2 + 3 = 0
Subtract 5 from both sides:
x = -5 or x^2 + 3 = 0
x = (0 ± sqrt(0^2 - 4×3))/2 = ( ± sqrt(-12))/2:
x = -5 or x = sqrt(-12)/2 or x = (-sqrt(-12))/2
sqrt(-12) = sqrt(-1) sqrt(12) = i sqrt(12):
x = -5 or x = (i sqrt(12))/2 or x = (-i sqrt(12))/2
sqrt(12) = sqrt(4×3) = sqrt(2^2×3) = 2sqrt(3):
x = -5 or x = (i×2 sqrt(3))/2 or x = (-i×2 sqrt(3))/2
(2 i sqrt(3))/2 = i sqrt(3):
x = -5 or x = i sqrt(3) or x = (-2 i sqrt(3))/2
(2 (-i sqrt(3)))/2 = -i sqrt(3):
Answer: x = -5 or x = i sqrt(3) or x = -i sqrt(3)
Answer:
C. x = −5, 1.7i, −1.7i
Step-by-step explanation:
Quick answer:
C. x = −5, 1.7i, −1.7i
explanation:
C. is the only answer option that does NOT have 0 as a root, which is impossible, because there is a constant term, which means that all roots are non-zero. In other words, we cannot extract x as a factor.
Complete answer:
All odd degree polynomials have at least one real root.
By the real roots theorem, we know that
if there is a real root, it must be of the form [tex]\pm[/tex]p/q where q is any of the factors of the leading coefficient (1 in this case) and p is any factor of the constant term d (15 in this case).
Values of [tex]\pm[/tex]p/q are
On trial and error, using the factor theorem, we see that
f(-5) = 0, therefore -5 is a real root. By long division, we have a quotient of x^2+3 = 0, which gives readily the remaining (complex) roots of +/- sqrt(5) i
The answer is {-5, +/- sqrt(5) i}, or again,
C. x = −5, 1.7i, −1.7i
Solve for x:
x/-6 ≥ -20?
Answer: x ≤ 120
Step-by-step explanation: To get x by itself in this inequality, since it's being divided by -6, we must multiply both sides by -6, just like we would if we were solving an equation, but here is the trick you have to watch out for with inequalities.
When you multiply or divide both sides of an inequality by a
negative, you must switch the direction of the inequality sign.
So our second step in this problem reads x ≤ 120.
Please give this idea your full attention.
Even the most advanced algebra students will sometimes forget to switch the direction of the inequality sign when multiplying or dividing both sides of an inequality by a negative.
Answer:
x ≤ 120
I hope this helps!
Which expression is equivalent to 8 square root 6 ?
Answer:
(2.13982638787^3) x 2
Find the slope of the line through the points (-4, 6) and (8,4).
I need help on this
Start with the slope formula.
m = y2-y1/x2 - x1
We take the second y minus the first y
over the second x minus the first x.
So we have 4 - 6/8 - -4.
This simplifies to -2/12 which reduces to -1/6.
PLEASE HELP! You do not have to answer all questions but can someone explain to me on where I am even suppose to begin? I don't even know how to answer a single one of these questions.
Step-by-step explanation:
For problems 1 through 15, evaluate the function at the given x value.
1. f(5) = 2(5) − 1 = 9
2. f(3) = 3² − 3(3) − 1 = -1
3. f(0) = 2(0) + 5 = 5
So on and so forth.
Then, match each answer with the corresponding letter.
The answer to #1 was 9. 9 corresponds to the letter A.
The answer to #2 was -1. -1 corresponds to the letter C.
The answer to #3 was 5. 5 corresponds to the letter P.
Finally, write each letter with its corresponding problem number.
So everywhere you see a 1, write A.
Everywhere you see a 2, write C.
Everywhere you see a 3, write P.
Continue until every blank has a letter and the problem is solved.
Answer:
For problems 1 through 15, evaluate the function at the given x value.
1. f(5) = 2(5) − 1 = 9
2. f(3) = 3² − 3(3) − 1 = -1
3. f(0) = 2(0) + 5 = 5
So on and so forth.
Step-by-step explanation:
a family spent $93 at a carnival.
*they spent $18 on tickets and $30 on food. they spent the rest of the money on games.
which equation can be used to to find "g", the amount of money used on games.
Answer: 93-(18+30)=g
93-48=g
45=g
Step-by-step explanation: yup
The answer is 93-18-30-g=0 or 18+30+g=93
(21x-3)+21=23x+6 solve
Answer:
False
Step-by-step explanation:
You Cnat solve it
Answer:
you cannot solve it
Step-by-step explanation:
false
Mrs. Simpson’s calculus class has an exam with an average score of 80 and standard deviation of 15. Assume that exam scores are normally distributed. If Mrs. Simpson decides to give an A grade to students who score in the top 20% of the class, what exam score is needed in order to get the A grade? (3pts)
Answer:
93 is the exam score needed in order to get the A grade in Mrs Simpson’s test
Step-by-step explanation:
Let x be the score that gives an A grade
Mathematically from the z-score formula, we know that;
z-score = x-mean/SD
From the question, x = ? , mean = 80 and SD = 15
Thus;
z-score = x-80/15
But in this question, we have the probability but we do not have the z-score
So we need the z-score that is equivalent to 20%
20% is same as 0.2
Using the standard normal distribution table, a probability of 0.2 corresponds to a z-score of 0.84
Thus, mathematically;
0.84 = x-80/15
x-80 = 15(0.84)
x-80 = 12.6
x = 80 + 12.6
x = 92.6 which is approximately 93
A person standing close to the edge on top of a 96-foot building throws a ball vertically upward. The quadratic function h = − 16 t 2 + 116 t + 96 models the ball's height above the ground, h , in feet, t seconds after it was thrown. a) What is the maximum height of the ball? b) How many seconds does it take until the ball hits the ground?
Answer: a) 306.25 feet b) 8 s
Step-by-step explanation:
Actually we have to find the function' s h(t) maximum meaning.
To do that we have to find the corresponding t - let call it t max
As known t max= (t1+t2)/2 where t1 and t2 are the roots of quadratic equation' s
Lets find the roots t1 and t2
-16*t^2+116*t+96=0 divide by 4 each side of the equation
-4*t^2 +29*t+24=0
D=29^2+24*4*4=1225 =35^2
t1=(-29-35)/(-8)=8
t2=(-29+35)/(-8)=-6/8=-3/4=-0.75
t max= (8+(-0.75))= 7,25/2=3.625 s
h max= -16*t max ^2+116*t +96= -16*3.625^2+116*3.625+96=306.25 feet
b) t2=8s is the time when the ball hits the ground.
Answer:
a) 306.25 ft
b) 8 seconds
Step-by-step explanation:
a) The time at the maximum height is found from the equation for the axis of symmetry:
ax^2 +bx +c has axis of symmetry at x=-b/(2a)
For the given equation, the t-value at the vertex is ...
t = -116/(2(-16)) = 3.625 . . . seconds
At that time, the height is ...
h = (-16(3.625) +116)(3.625) +96 = (58)(3.625) +96 = 306.25
The maximum height is 306.25 feet.
__
b) The ball will hit the ground when h=0. From the vertex values in the first part, we know we can rewrite the equation in vertex form as ...
h(t) = -16(t -3.625)^2 +306.25
This will be 0 when ...
0 = -16(t -3.625)^2 +306.25
(t -3.625)^2 = 306.25/16
t = 3.625 +√19.140625 = 3.625 +4.375 = 8
The ball will hit the ground after 8 seconds.
How many times does 1/4 go into 3/8
Answer:
3/2
Step-by-step explanation:
3/8 ÷ 1/4
Copy dot flip
3/8 * 4/1
12/8
Divide top and bottom by 4
3/2
The residents of a city voted on whether to raise property taxes. The ratio of yes votes to no votes was 5 to 6. If there were 4508 no votes, what was the total
number of votes
Answer:
total number of votes was 8265.
Step-by-step explanation:
Ratio of yes to no votes = 5:6
we know by rule of indices that
a/b = a*x/b*x
let the no. of people who voted yes be 5x
the no. of people who voted no be 6x
Thus, total no of votes = 5x+6x= 11x
given that
If there were 4508 no votes
thus,
6x = 4508
x = 4508/6 = 751 1/3 = 751.33
Thus, total no. of votes = 11 x = 11* 751.33 = 8264.63
rounding it to next integral no. as no. of votes cannot be fraction or decimal
the total number of votes was 8265.
What is the 50th term of the arithmetic sequence having u(subscript)1 = -2 and d = 5
Answer:
243
Step-by-step explanation:
The general term for this arithmetic sequence is:
a(n) = -2 + 5(n - 1).
Then a(50) = -2 + 5(49) = 243
2⁶ × 2⁵ how do i simplify this?
Answer:
2^11
Step-by-step explanation:
since the bases are the same, we can add the exponents
a^b * a^c = a^(b+c)
2^6 * 2^5
2^(6+5)
2^11
What is 2-(-8)????? And how do you solve it????
Subtracting a negative is the same as adding a positive. So 2-(-8) is really 2+8 = 10.
With something like 2-8, we start at 2 and move to the left 8 units to arrive at -6 on the number line. When we do 2-(-8), we start at 2 and move 8 units in the opposite direction since -8 is the opposite of 8.
In terms of money, you can think of a negative number as an IOU or it represents the amount of debt. Writing -8 means you are 8 dollars in debt. If we subtract away debt, then we have less of it and effectively its the same as adding dollars to your pocket. Subtracting away 8 dollars of debt is the same as adding 8 dollars to your pocket, which is one interpretation of how 2-(-8) is the same as 2+8.
What are the following fractions from least to greatest 3/8 5/8 4/8 2/8 7/8
Answer:
2/8, 3/8, 4/8, 5/8, 7/8. If there are more numbers I apologize, I see 2 boxes that say "obj" instead.
A highway department executive claims that the number of fatal accidents which occur in her state does not vary from month to month. The results of a study of 140 fatal accidents were recorded. Is there enough evidence to reject the highway department executive's claim about the distribution of fatal accidents between each month? Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Fatal Accidents 8 15 9 8 13 6 17 15 10 9 18 12
Answer:
There is enough evidence to reject the highway department executive's claim about the distribution of fatal accidents between each month, as the Variance is 14 and the Standard Deviation = 4 approximately.
There is a high degree of variability in the mean of the population as explained by the Variance and the Standard Deviation.
Step-by-step explanation:
Month No. of Mean Squared
Fatal Accidents Deviation Difference
Jan 8 -4 16
Feb 15 3 9
Mar 9 -3 9
Apr 8 -4 16
May 13 1 1
Jun 6 -6 36
Jul 17 5 25
Aug 15 3 9
Sep 10 -2 4
Oct 9 -3 9
Nov 18 6 36
Dec 12 0 0
Total 140 170
Mean = 140/12 = 12 Mean of squared deviation (Variance) = 170/12 = 14.16667
Standard deviation = square root of variance = 3.76386 = 4
The fatal accidents' Variance is a measure of how spread out the fatal accident data set is. It is calculated as the average squared deviation of the number of each month's accident from the mean of the fatal accident data set. It also shows how variable the data varies from the mean of approximately 12.
The fatal accidents' Standard Deviation is the square root of the variance, and a useful measure of variability when the distribution is normal or approximately normal.
Josephine has a rectangular garden with an area of 2x2 + x – 6 square feet. A rectangle labeled 2 x squared + x minus 6 Which expressions can represent the length and width of the garden? length = x2 – 3 feet; width = 2 feet length = 2x + 3 feet; width = x – 2 feet length = 2x + 2 feet; width = x – 3 feet length = 2x – 3 feet; width = x + 2 feet
Answer:
2x^2 + x - 6 = rectangular garden: length = 2x – 3 feet; width = x + 2 feet
Step-by-step explanation:
(2x - 3)(x + 2) = 2x^2 + x - 6 =
2x^2 + 4x - 3x - 6 = 2x^2 + x - 6 =
2x^2 + x - 6
You get the original equation from the two sides multiplied. :)
Hope this helps, have a good day.
The length and width of the rectangle will be (2x – 3) and (x + 2). Then the correct option is D.
What is the area of the rectangle?Let W be the rectangle's width and L its length.
The area of the rectangle is the multiplication of the two different sides of the rectangle. Then the rectangle's area will be
Area of the rectangle = L × W square units
The area is 2x² + x – 6 square feet. Then the factor of the equation is given as,
A = 2x² + x – 6
A = 2x² + 4x – 3x – 6
A = 2x(x + 2) – 3(x + 2)
L × W = (2x – 3)(x + 2)
The length and width of the rectangle will be (2x – 3) and (x + 2). Then the correct option is D.
More about the area of the rectangle link is given below.
https://brainly.com/question/20693059
#SPJ6
Test the age of the participants (AGE1) against the null hypothesis H0 = 34. Use a one-sample t-test. How would you report the results?
Answer:
t = -1.862, df = 399, p > 0.05
Step-by-step explanation:
The null hypothesis is the statement which is test for its validity. The decision to accept or reject the null hypothesis is based on the test statistics value. In the given question the null hypothesis is H0 = 34. There is one sample t-test for the testing of null hypothesis. The null hypothesis will be same for each type of one sample t-test. The null hypothesis assumes that the difference between the true mean and comparison value is zero.
When you enter the Texas Turnpike, they give you a ticket showing the time and place of your entry. When you exit, you turn in this ticket and they use it to figure your toll. Because they know the distance between toll stations, they can also use it to check your average speed against the turnpike limit of 65 mph. On your trip, heavy snow limits your speed to 40 mph for the first 120 mi. At what average speed can you drive for the remaining 300 mi without having your ticket prove that you broke the speed limit?
Answer:
87 mph
Step-by-step explanation:
Total distance needed is 120 mi + 300 mi and that is 420 mi.
Driving at 65 mph means that it would take
420 / 65 hours to reach his destination.
6.46 hours .
at the first phase, he drove at 40 mph for 120 mi, this means that it took him
120 / 40 hours to complete the journey.
3 hours.
the total time needed for the whole journey is 6.46 hours, and he already spent 3 hours in the first phase. To keep up with the 6.46 hours required, in the second phase, he has to drive at a speed of
6.46 - 3 hours = 3.46 hours.
300 mi / 3.46 hours => 86.71 mph approximately 87 mph
Therefore, he needs to drive at not more than 87 mph to keep up with the journey while not breaking his speed limit
What is the exact distance from (−1, 4) to (6, −2)? square root of 80. units square root of 82. units square root of 85. units square root of 89. units
Answer:
[tex]\sqrt{85}[/tex].
Step-by-step explanation:
[tex]x[/tex]-coordinates:
First point: [tex]-1[/tex].Second point: [tex]6[/tex].Difference: [tex]|-1 - 6| = |-7| = 7[/tex].[tex]y[/tex]-coordinates:
First point: [tex]4[/tex].Second point: [tex]-2[/tex].Difference: [tex]|4 - (-2)| = |6| = 6[/tex].Refer to the diagram attached. Consider these two points as the two end points of the hypotenuse of a right triangle. The lengths of the two legs are equal to:
the difference between the two [tex]x[/tex]-coordinates, [tex]7[/tex], and the difference between the two [tex]y[/tex]-coordinates, [tex]6[/tex].Apply Pythagorean Theorem to find the length of the hypotenuse (which is equal to the distance between the two points in question.)
[tex]\begin{aligned}\text{Hypotenuse} &= \sqrt{(\text{First Leg})^2 + (\text{Second Leg})^2} \\ &= \sqrt{7^2 + 6^2} \\ &= \sqrt{85}\end{aligned}[/tex].
Answer:
C
Step-by-step explanation:
Pulse rates of women are normally distributed with a mean of 77.5 beats per minute and a standard deviation of 11.6 beats per minute.
1. What are the values of the mean and standard deviation after converting all pulse rates of women to z scores using z = (x - mu )?
2. What are the units of the corresponding z scores?
A. The z scores are measured with units of "beats per minute".
B. The z scores are measured with units of "minutes per beat".
C. The z scores are measured with units of "beats."
D. The z scores are numbers without units of measurement.
Answer:
D. The z scores are numbers without units of measurement.
Step-by-step explanation:
Z-scores are without units, or are pure numbers.
Find the inverse of the following function.
Answer:
The inverse is 1/64 x^2 = y x ≥ 0
Step-by-step explanation:
f(x) = 8 sqrt(x)
y = 8 sqrt(x)
Exchange x and y
x = 8 sqrt (y)
Solve for y
Divide each side by 8
1/8 x = sqrt(y)
Square each side
(1/8 x)^2 = (sqrt(y))^2
1/64 x^2 = y
The inverse is 1/64 x^2 = y x ≥ 0
since x ≥0 in the original function
Answer:
[tex]\Huge \boxed{\mathrm{D}}[/tex]
Step-by-step explanation:
[tex]f(x)=8\sqrt{x}[/tex]
[tex]\sf Replace \ with \ y.[/tex]
[tex]y=8\sqrt{x}[/tex]
[tex]\sf Switch \ the \ variables.[/tex]
[tex]x= 8\sqrt{y}[/tex]
[tex]\sf Divide \ both \ sides \ of \ the \ equation \ by \ 8.[/tex]
[tex]\displaystyle \frac{x}{8} =\sqrt{y}[/tex]
[tex]\sf Square \ both \ sides \ of \ the \ equation.[/tex]
[tex]\displaystyle (\frac{x}{8} )^2 =y[/tex]
[tex]\displaystyle \frac{x^2 }{64} =y[/tex]
[tex]\displaystyle f^{-1}(x)=\frac{1}{64} x^2[/tex]
The diameter, D, of a sphere is 7.8mm. Calculate the sphere's volume, V.
Use the Value 3.15 for pie.
Answer:
249.14 mm³
Step-by-step explanation:
r = diameter/2
= 7.8 /2
volume = 4/3 π r³
= 4/3 * 3.15 * (7.8/2)³
= 249.14 mm³
Select the function that represents a parabola with zeros at x = –2 and x = 4, and y-intercept (0,–16). A ƒ(x) = x2 + 2x – 8 B ƒ(x) = 2x2 + 4x – 16 C ƒ(x) = x2 – 2x – 8 D ƒ(x) = 2x2 – 4x – 16
Answer:
D. [tex]f(x) = 2\cdot x^{2}-4\cdot x -16[/tex]
Step-by-step explanation:
Any parabola is modelled by a second-order polynomial, whose standard form is:
[tex]y = a\cdot x^{2}+b\cdot x + c[/tex]
Where:
[tex]x[/tex] - Independent variable, dimensionless.
[tex]y[/tex] - Dependent variable, dimensionless.
[tex]a[/tex], [tex]b[/tex], [tex]c[/tex] - Coefficients, dimensionless.
In addition, a system of three linear equations is constructed by using all known inputs:
(-2, 0)
[tex]4\cdot a -2\cdot b + c = 0[/tex] (Eq. 1)
(4, 0)
[tex]16\cdot a + 4\cdot b +c = 0[/tex] (Eq. 2)
(0,-16)
[tex]c = -16[/tex] (Eq. 3)
Then,
[tex]4\cdot a - 2\cdot b = 16[/tex] (Eq. 4)
[tex]16\cdot a + 4\cdot b = 16[/tex] (Eq. 5)
(Eq. 3 in Eqs. 1 - 2)
[tex]a - 0.5\cdot b = 4[/tex] By Eq. 4 (Eq. 4b)
[tex]a = 4 + 0.5\cdot b[/tex]
Then,
[tex]16\cdot (4+0.5\cdot b) + 4\cdot b = 16[/tex] (Eq. 4b in Eq. 5)
[tex]64 + 12\cdot b = 16[/tex]
[tex]12\cdot b = -48[/tex]
[tex]b = -4[/tex]
The remaining coeffcient is:
[tex]a = 4 + 0.5\cdot b[/tex]
[tex]a = 4 + 0.5\cdot (-4)[/tex]
[tex]a = 2[/tex]
The function that represents a parabola with zeroes at x = -2 and x = 4 and y-intercept (0,16) is [tex]f(x) = 2\cdot x^{2}-4\cdot x -16[/tex]. Thus, the right answer is D.
Answer:
D ƒ(x) = 2x2 – 4x – 16
Step-by-step explanation:
Which of the following correctly shows the quotient of 80 divided by 5 ?
Answer:16
Step-by-step explanation:
Just divide 80 by 5 or skip count by fives.
Find x. A. 3√3 B. 3 C. 2√3/3 D. √63
Answer:
[tex]\huge\boxed{\sf x = 3\sqrt{3}}[/tex]
Step-by-step explanation:
Cos 30 = Adjacent / Hypotenuse
Where Adjacent = x , Hypotenuse = 6
[tex]\frac{\sqrt{3} }{2}[/tex] = x / 6
x = [tex]\frac{\sqrt{3} }{2}[/tex] * 6
[tex]\sf x = 3\sqrt{3}[/tex]
2. Imagine you are one of the people who left the luncheon with a contagious disease and interacted with an average of 9 different people each day. How many people could potentially be infected in 7 days
Answer:
63 people.
Step-by-step explanation:
If you have a contagious disease and met with 9 different people each day for 7 days, that'll be 63 people that have gotten infected. 9 x 7 = 63. Hope this helps you!
what is the domain of this
Answer:
[tex]\boxed{\sf B. \ All \ real \ numbers}[/tex]
Step-by-step explanation:
The domain is all possible values for x.
[tex]f(x)=(\frac{1}{4} )^x[/tex]
There are no restrictions on x.
The domain is all real numbers.
Answer:
B.All real number
hope you have unterstand
HELP ASAP PLEASE!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
Option (B)
Step-by-step explanation:
The given expression is,
[tex]\sqrt{22x^6}\div\sqrt{11x^4}[/tex]
We can rewrite this expression as,
[tex]\frac{\sqrt{22x^6}}{\sqrt{11x^4} }[/tex]
Solving it further,
[tex]\frac{\sqrt{22x^6}}{\sqrt{11x^4} }=\frac{\sqrt{22(x^3)^2} }{\sqrt{11(x^2)^2} }[/tex] [Since [tex]x^3\times x^3=x^6[/tex] and [tex]x^{2}\times x^{2}=x^4[/tex]]
[tex]=\sqrt{\frac{22(x^3)^2}{11(x^2)^2} }[/tex] [Since [tex]\frac{\sqrt{a} }{\sqrt{b} }=\sqrt{\frac{a}{b} }[/tex]]
[tex]=\frac{x^3}{x^2}\sqrt{\frac{22}{11} }[/tex]
[tex]=x\sqrt{2}[/tex]
Therefore, quotient will be x√2.
Option (B) will be the correct option.
I don’t really get this question
You can put [tex]n[/tex] different elements in order in [tex]n![/tex] different ways.
So, you can visit 12 different cities in [tex]12!=479001600[/tex] different ways.
Answer: 479,001,600
Step-by-step explanation:
There are 12 ways to go to the first place, 11 for the second, ten for the third, and so on. So 12! Means 12x11x10x9x8x7x6x5x4x3x2x1.
Let E and F be two events of an experiment with sample space S. Suppose P(E) = 0.6, P(F) = 0.3, and P(E ∩ F) = 0.1. Compute the values below.
(a) P(E ∪ F) =
(b) P(Ec) =
(c) P(Fc ) =
(d) P(Ec ∩ F) =
Answer:
(a) P(E∪F)= 0.8
(b) P(Ec)= 0.4
(c) P(Fc)= 0.7
(d) P(Ec∩F)= 0.8
Step-by-step explanation:
(a) It is called a union of two events A and B, and A ∪ B (read as "A union B") is designated to the event formed by all the elements of A and all of B. The event A∪B occurs when they do A or B or both.
If the events are not mutually exclusive, the union of A and B is the sum of the probabilities of the events together, from which the probability of the intersection of the events will be subtracted:
P(A∪B) = P(A) + P(B) - P(A∩B)
In this case:
P(E∪F)= P(E) + P(F) - P(E∩F)
Being P(E) = 0.6, P(F) = 0.3 and P(E ∩ F) = 0.1
P(E∪F)= 0.6 + 0.3 - 0.1
P(E∪F)= 0.8
(b) The complement of an event A is defined as the set that contains all the elements of the sample space that do not belong to A. The Complementary Rule establishes that the sum of the probabilities of an event and its complement must be equal to 1. So, if P (A) is the probability that an event A occurs, then the probability that A does NOT occur is P (Ac) = 1- P (A)
In this case: P(Ec)= 1 - P(E)
Then: P(Ec)= 1 - 0.6
P(Ec)= 0.4
(c) In this case: P(Fc)= 1 - P(F)
Then: P(Fc)= 1 - 0.3
P(Fc)= 0.7
(d) The intersection of two events A and B, designated as A ∩ B (read as "A intersection B") is the event formed by the elements that belong simultaneously to A and B. The event A ∩ B occurs when A and B do at once.
As mentioned, the complementary rule states that the sum of the probabilities of an event and its complement must equal 1. Then:
P(Ec intersection F) + P(E intersection F) = P(F)
P(Ec intersection F) + 0.1 = 0.3
P(Ec intersection F)= 0.2
Being:
P(Ec∪F)= P(Ec) + P(F) - P(Ec∩F)
you get:
P(Ec∩F)= P(Ec) + P(F) - P(Ec∪F)
So:
P(Ec∩F)= 0.4 + 0.3 - 0.2
P(Ec∩F)= 0.8
