# Probability & Usage Guarantee

11. A statistics instructor collected data on the time it takes the students to complete a test. The test taking time is uniformly distributed within a range of 35 minutes to 55 minutes.

a. Determine the height.

b. How long does the typical test taking time?

c. Determine the standard deviation of the test taking time.

d. What is the probability a particular student will take less than 45 minutes?

e. What is the probability a particular student will take between 45 and 50 minutes?

13. A certain printer cartridge has demonstrated a mean time usage of 9 hours and a standard deviation of 22 minutes. What time usage guarantee (in hours) should the manufacturer advertise in order to ensure that only 4% of the cartridges fail to meet the guaranteed time usage?

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#### Solution Summary

This solution discusses probability and usage guarantees.