# 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

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I only see partial conversation and what's the question here!
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Damian
yes that's correct
Professor
I think
Professor
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LITNING
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Santosh
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Mahi
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Anam
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Anam
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Bob
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brayan
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Damian
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Renato
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?
Kyle
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why?
what school?
Kyle
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Joe
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research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
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Loga
what does nano mean?
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Bharti
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