Q1.A survey of 200 college graduates who have been working for at least 3 years found that 90 owned only mutual funds, 20 owned only stocks, and 70 owned both.
a. What is the probability that an individual owns a stock? A mutual fund?
b. What is the probability that an individual owns neither stocks nor mutual funds?
c. What is the probability that an individual owns either a stock or a mutual fund?
Q2.A study of nonfatal occupational injuries in the United States found that about 31% of all injuries in the service sector involved the back. The National Institute for Occupational Safety and Health (NIOSH) recommended conducting a comprehensive ergonomics assessment of jobs and workstation’s. In response to this information, mark Glass-Meyer developed a unique ergonomic handcart to help field service engineers be more productive and also to reduce back injuries from lifting parts and equipment during service calls. Using a simple 382 field service engineers who were provided with these carts. Mark collected the following data.
Year 1 Year2
Average call time 8.27 hours 7.98 hours
Standard deviation 1.36 hours 1.21 hours
Proportion of back Injuries 0.018 0.010
Find the 95% confidence intervals for the average call times and proportion of back injuries in each years. What conclusions would you reach based on your results?