Claim: The standard deviation of pulse rates of adult males is less than   10   bpm. For a random sample of 155   adult​ males, the pulse rates have a standard deviation of 9.7   bpm. Find the value of the test statistic.

The lifetime of a light bulb is normally distributed with an average life of 500 hours and a standard deviation of 100 hours.  If a company installs 5000 of these light bulbs, find the number of bulbs that can be expected to last between 500 hours and 675 hours.

A bank loan officer rates applicants for credit. The ratings can be described by a normal model with a mean of 200 and a standard deviation of 50. If an applicant is randomly selected, what percentage can be expected to be between 200 and 275?

Use z scores to compare the given values. In a recent awards ceremony, the age of the winner for best actor was 39 and the age of the winner for best actress was 58. For all best actors, the mean age is 47.5 years and the standard deyiation is 8.2 years. For all best actresses, the mean age is 38.6 years and the standard deviation is 10.7 years. (All ages are determined at the time of the awards ceremony.) Relative to their genders, who had the more extreme age when winning the award, the actor or the actress? Explain. Since the z score for the actor is z= and the z score for the actress is z= the actresS had the more extreme age. (Round to two decimal places.)