11.9 Review

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

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

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
• d

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.

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 $X$ .

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 $X$ .

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

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

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

Find the 90th percentile of waiting time in minutes.

Find the median waiting time for one student.

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