Summary: Practice final exam for use with Collaborative Statistics (col10522) by Barbara Illowsky and Susan Dean.

Assume the amount of money seventh–grade students spend on food each day at school is exponentially distributed with an average of $2.50.

Which graph best describes the distribution?

**A.****B.****C.****D.**

B

Find the probability that a randomly selected seventh–grade student spends less than $4 a day on food.

**A.**0.7981**B.**0.2019**C.**0.9999**D.**0.0001

A

85% of the seventh–grade students spend more than what amount per day?

**A.**$2.12**B.**$0.75**C.**$4.74**D.**$0.41

D

The amount of time that intermediate algebra students at Leland High School spend doing their homework per day is normally distributed with a mean 1.5 hours and standard deviation 0.75 hours.

If one student is randomly chosen, what is the probability that the student does intermediate algebra homework at least 2 hours per day?

**A.**0.7475**B.**0.4259**C.**0.2525**D.**0.6784

C

60% of these students spend at most how many hours doing their homework?

**A.**1.69 hours**B.**1.31 hours**C.**1.5 hours**D.**0.2533 hours

A

Llamas are excellent pack animals. It is known that the weight of supplies carried by llamas follows a normal distribution with a mean of 62.5 pounds and a standard deviation of 6 pounds.

Find the probability that the weight of supplies carried by one randomly chosen llama is between 60 and 70 pounds.

**A.**0.4441**B.**0.5559**C.**0.8944**D.**1

B

The middle 50% of weights of supplies carried by a randomly chosen llama is between _____ and _____.

**A.**0 and 62.5 pounds**B.**58.45 and 66.55 pounds**C.**56.5 and 68.5 pounds**D.**There is not enough information given.

B

Which of the following are true for the normal distribution?

**I.**More values fall close to the mean than fall far away from the mean.**II.**The mean and standard deviation cannot be the same.**III.**A change in µ causes the graph to shift to the left or right and changes the shape of the graph.**IV.**A change in s causes a change in the shape of the normal curve.

**A.**I, IV**B.**I, II, III, IV**C.**I, II, III**D.**III, IV

A

The length of time junior high school students sleep per night follows an approximate uniform distribution from seven to eleven hours. Suppose we randomly select a junior high student.

Find the probability that the randomly selected student sleeps less than 8 1/2 hours per night.

**A.**.2143**B.**0.7727**C.**0.4705**D.**0.375

D

Find the probability that the randomly selected student sleeps eight to twelve hours per night.

**A.**0**B.**1**C.**0.75**D.**0.25

C

On average, how long does a junior high school student sleep per night?

**A.**.2143**B.**0.7727**C.**0.4705**D.**0.375

B

On average, how long does a junior high school student sleep per night?

**A.**9.6 hours**B.**6.5 hours**C.**7.8 hours**D.**8.4 hours

D

We are interested in the probability that a randomly selected student sleeps less than eight hours, knowing that he/she sleeps less than ten. Which graph best depicts this situation?

**A.****B.****C.****D.**

C