Chapter 6 Review

A normal distribution has a mean of 653 and a standard deviation of 53. Use the Empirical rule to find an interval about the mean in which 68% of the data will fall.

• 600-706

• 600-653

• 653-706

• 547-759

A normal distribution has a mean of 653 and a standard deviation of 53. Estimate the range of values about the mean in which 95% of the data will fall.

• 600-709

• 547-653

• 653-759

• 547-759

The Customer Service Center in a large New York department store has determined that the amount of time spent with a customer about a complaint is normally distributed with a mean of 9.3 minutes and a standard deviation of 2.5 minutes. What is the probability that for a randomly chosen customer with a complaint the amount of time spent resolving the complaint will be shorter than 11.8 minutes?

• 34%

• 84%

• 97%

• 15%

The Customer Service Center in a large New York department store has determined that the amount of time spent with a customer about a complaint is normally distributed with a mean of 9.3 minutes and a standard deviation of 2.5 minutes. What is the probability that for a randomly chosen customer with a complaint the amount of time spent resolving the complaint will be longer than 4.3 minutes?

• 97.5%

• 16%

• 50%

• 84%

The Customer Service Center in a large New York department store has determined that the amount of time spent with a customer about a complaint is normally distributed with a mean of 9.3 minutes and a standard deviation of 2.5 minutes. What is the probability that for a randomly chosen customer with a complaint the amount of time spent resolving the complaint will be between 6.8 and 14.3 minutes?

• 16%

• 34%

• 81.5%

• 97%

Quick Start Company makes 12-volt car batteries. After many years of product testing, the company knows that the average life of a Quick Start battery is normally distributed, with a mean of 45 months and a standard deviation of 8 months. If Quick Start does not want to make refunds for more than 10% of its batteries under the full-refund guarantee policy, for how long should the company guarantee the batteries (to the nearest month)?

• 33 months

• 34 months

• 35 months

• 36 months

On a practical nursing licensing exam, the mean score is 79 and the standard deviation is 9 points. What is the standardized score of a student with a raw score of 87?

• 8.67

• .89

• 18.4

• 8

On a practical nursing licensing exam, the mean score is 79 and the standard deviation is 9 points. What is the standardized score of a student with a raw score of 79?

• 0

• 1

• 2

• 3

Express Courier Service has found that the delivery time for packages is normally distributed with mean 14 hours and standard deviation 2 hours. What is the probability that a package selected at random will be delivered in 18 hours or less?

• .0228

• .5263

• .4737

• .9772

For a standard normal distribution find the area to the left of z = 1.34

• .0901

• .9099

• .8121

• .1879