The life expectancy of a laser-printer toner cartridge varies considerably according to the toner and drum type, and how the cartridge is used. Printed pages containing lots of graphics require more toner, while pages with mostly text require considerably less toner. Page coverage is usually measured as a proportion (or percentage). For example, a typical text page has approximately 0.05 coverage. A random sample of printed pages from an office printer was obtained, and the page coverage was carefully measured. Is there any evidence to suggest the data are from a non-normal population?
Jockeys in the United States and England work very hard to keep their weight down. Many participate in weight-loss programs, carefully monitor their diet, and exercise regularly. The weight of a male jockey is approximately normal with mean 52 kg and standard deviation 1.2 kg. Suppose a male jockey is randomly selected.
a. What is the probability that the jockey weighs more than 53 kg?
b. What is the probability that the jockey weighs between 50 and 54 kg?
c. Find a value w such that 80% of all male jockeys weigh more than w.
d. Suppose the jockey selected weighs 57 kg. Is there any evidence to suggest the claimed mean (52 kg) is wrong? Justify your answer.
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