Z-Scores and TI-84 Calculations

This video tutorial explains how to solve a problem using the TI-84 graphing calculator. It covers the company's car retirement policy based on a normal distribution of months in service, with a mean of 39 months and a standard deviation of 5 months. The tutorial demonstrates calculating the percentage of cars in service between 44 and 54 months using the TI-84 and Z-scores, comparing results with the empirical rule.

What is the mean number of months in service for the fleet of cars?

• 5 months

• 44 months

• 39 months

• 54 months

Which rule is mentioned as an alternative to using the TI-84 calculator?

• Empirical Rule

• Central Limit Theorem

• Pythagorean Theorem

• Binomial Theorem

What is the first step in using the TI-84 calculator to find the percentage of cars in service?

• Enter the upper X-value

• Enter the mean value

• Enter the standard deviation

• Enter the lower X-value

What percentage of cars remain in service between 44 and 54 months according to the TI-84 calculator?

• 16.00%

• 15.85%

• 14.50%

• 15.73%

How does the percentage calculated by hand using the empirical rule compare to the calculator's result?

• It is slightly lower

• It is significantly different

• It is exactly the same

• It is slightly higher

What does a Z-score represent in the context of this problem?

• The average miles driven

• The total number of cars

• The distance of a data value from the mean

• The number of months a car is in service

What is the Z-score for a car in service for 44 months?

• 2

• 0

• 3

• 1

What is the Z-score for a car in service for 54 months?

• 0

• 3

• 1

• 2

When using Z-scores on the TI-84, what are the mean and standard deviation values?

• Mean = 39, SD = 5

• Mean = 0, SD = 1

• Mean = 1, SD = 0

• Mean = 5, SD = 39

What percentage of cars remain in service between Z-scores of 1 and 3 according to the TI-84 calculator?

• 16.00%

• 15.85%

• 15.73%

• 14.50%