QM 3341: Business Statistics
Practice Problems: Chapter 10
1. The quality control manager at a light bulb factory needs to determine whether the
mean life of a large shipment of light bulbs is equal to 375 hours. The population
standard deviation is 100 h
1. A research shows that people with a bachelors degree who transferred from a community
college earn less than those who start at a four-year school. The population standard
deviation is $4400 for graduates transferred from a community
1. According to a Health Department report, female residents have a higher average life
expectancy as compared to male residents. The historical standard deviation of 8.2 years for
females and 8.6 years for males.
A recent study focused on the number of times men and women send a Twitter message in a
day. The information is summarized below.
At the .01 significance l