# 10.2 Review questions

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Copy of Review Questions module m17021 (http://cnx.org/content/ m17021/) from Collaborative Statistics by Dean and Illowsky http://cnx.org/content/col10522/ , 12/18/2008 . The FORMAT only of the question numbering has been changed.

The next three questions refer to the following information:

In a survey at Kirkwood Ski Resort the following information was recorded:

 0 – 10 11 - 20 21 - 40 40+ Ski 10 12 30 8 Snowboard 6 17 12 5

Suppose that one person from of the above was randomly selected.

Find the probability that the person was a skier or was age 11 – 20.

REVIEW QUESTION 1 Solution : $\frac{\text{77}}{\text{100}}$

Find the probability that the person was a snowboarder given he/she was age 21 – 40.

REVIEW QUESTION 2 Solution : $\frac{\text{12}}{\text{42}}$

Explain which of the following are true and which are false.

• ## A

Sport and Age are independent events.
• ## B

Ski and age 11 – 20 are mutually exclusive events.
• ## C

$P\left(\text{Ski}\phantom{\rule{2pt}{0ex}}\text{and}\phantom{\rule{2pt}{0ex}}\text{age}\phantom{\rule{2pt}{0ex}}\text{21}-\text{40}\right)
• ## D

$P\left(\text{Snowboard}\phantom{\rule{2pt}{0ex}}\text{or}\phantom{\rule{2pt}{0ex}}\text{age}\phantom{\rule{2pt}{0ex}}0-\text{10}\right)

False

False

True
• ## D

False

The average length of time a person with a broken leg wears a cast is approximately 6 weeks. The standard deviation is about 3 weeks. Thirty people who had recently healed from broken legs were interviewed. State the distribution that most accurately reflects total time to heal for the thirty people.

REVIEW QUESTION 4 Solution : $N\left(\text{180},\text{16}\text{.}\text{43}\right)$

The distribution for $X$ is Uniform. What can we say for certain about the distribution for $\overline{X}$ when $n=1$ ?

• ## A

The distribution for $\overline{X}$ is still Uniform with the same mean and standard dev. as the distribution for $X$ .
• ## B

The distribution for $\overline{X}$ is Normal with the different mean and a different standard deviation as the distribution for $X$ .
• ## C

The distribution for $\overline{X}$ is Normal with the same mean but a larger standard deviation than the distribution for $X$ .
• ## D

The distribution for $\overline{X}$ is Normal with the same mean but a smaller standard deviation than the distribution for $X$ .

REVIEW QUESTION 5 Solution : A

The distribution for $X$ is uniform. What can we say for certain about the distribution for $\sum X$ when $n=50$ ?

• ## A

The distribution for $\sum X$ is still uniform with the same mean and standard deviation as the distribution for $X$ .
• ## B

The distribution for $\sum X$ is Normal with the same mean but a larger standard deviation as the distribution for $X$ .
• ## C

The distribution for $\sum X$ is Normal with a larger mean and a larger standard deviation than the distribution for $X$ .
• ## D

The distribution for $\sum X$ is Normal with the same mean but a smaller standard deviation than the distribution for $X$ .

REVIEW QUESTION 6 Solution : C

The next three questions refer to the following information:

A group of students measured the lengths of all the carrots in a five-pound bag of baby carrots. They calculated the average length of baby carrots to be 2.0 inches with a standard deviation of 0.25 inches. Suppose we randomly survey 16 five-pound bags of baby carrots.

State the approximate distribution for $\overline{X}$ , the distribution for the average lengths of baby carrots in 16 five-pound bags. $\overline{X}\text{~}$

REVIEW QUESTION 7 Solution : $N\left(2\text{,}\frac{\text{.25}}{\sqrt{\text{16}}}\right)$

Explain why we cannot find the probability that one individual randomly chosen carrot is greater than 2.25 inches.

## Review question 8 solution

We do not know the probability distribution for the underlying population of lengths of the individual carrots.

Find the probability that $\overline{X}$ is between 2 and 2.25 inches.

REVIEW QUESTION 9 Solution : 0.5000

The next three questions refer to the following information:

At the beginning of the term, the amount of time a student waits in line at the campus store is normally distributed with a mean of 5 minutes and a standard deviation of 2 minutes.

Find the 90th percentile of waiting time in minutes.

REVIEW QUESTION 10 Solution : 7.6

Find the median waiting time for one student.

REVIEW QUESTION 11 Solution : 5

Find the probability that the average waiting time for 40 students is at least 4.5 minutes.

REVIEW QUESTION 12 Solution : 0.9431

show that the set of all natural number form semi group under the composition of addition
what is the meaning
Dominic
explain and give four Example hyperbolic function
_3_2_1
felecia
⅗ ⅔½
felecia
_½+⅔-¾
felecia
The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
Pawel
2. (x) + (x + 2) = 60 2x + 2 = 60 2x = 58 x = 29 29, 30, & 31
Pawel
ok
Ifeanyi
on number 2 question How did you got 2x +2
Ifeanyi
combine like terms. x + x + 2 is same as 2x + 2
Pawel
x*x=2
felecia
2+2x=
felecia
×/×+9+6/1
Debbie
Q2 x+(x+2)+(x+4)=60 3x+6=60 3x+6-6=60-6 3x=54 3x/3=54/3 x=18 :. The numbers are 18,20 and 22
Naagmenkoma
Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
Pawel
how do I set up the problem?
what is a solution set?
Harshika
find the subring of gaussian integers?
Rofiqul
hello, I am happy to help!
Abdullahi
hi mam
Mark
find the value of 2x=32
divide by 2 on each side of the equal sign to solve for x
corri
X=16
Michael
Want to review on complex number 1.What are complex number 2.How to solve complex number problems.
Beyan
yes i wantt to review
Mark
16
Makan
x=16
Makan
use the y -intercept and slope to sketch the graph of the equation y=6x
how do we prove the quadratic formular
Darius
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
thank you help me with how to prove the quadratic equation
Seidu
may God blessed u for that. Please I want u to help me in sets.
Opoku
what is math number
4
Trista
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
can you teacch how to solve that🙏
Mark
Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
Brenna
(61/11,41/11,−4/11)
Brenna
x=61/11 y=41/11 z=−4/11 x=61/11 y=41/11 z=-4/11
Brenna
Need help solving this problem (2/7)^-2
x+2y-z=7
Sidiki
what is the coefficient of -4×
-1
Shedrak
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Jeannette has $5 and$10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
What is the expressiin for seven less than four times the number of nickels
How do i figure this problem out.
how do you translate this in Algebraic Expressions
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
how did you get the value of 2000N.What calculations are needed to arrive at it
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