To determine whether they have a certain disease, 100 people are to have their blood tested. however, rather than testing each individual separately, it has been decided first to place the people into groups of 10. the blood samples of the 10 people in each group will be pooled and analyzed together. if the test is negative, one test will suffice for the 10 people, whereas if the test is positive, each of the 10 people will also be individually tested and, in all, 11 tests will be made on this group. assume that the probability that a person has the disease is 0.1 for' all people, independently of one another, and compute the expected number of tests necessary for each group. (note that we are assuming that the pooled test will be positive if at least one person in the pool has the disease.)

An engineer is going to redesign an ejection seat for an airplane. the seat was designed for pilots weighing between 120 lb and 161 lb. the new population of pilots has normally distributed weights with a mean of 125 lb and a standard deviation of 28.1 lb. a)if a pilot is randomly selected, find the probability that his weight is between 120 lb and 161 lb.the probability is approximately? b. if 36 different pilots are randomly selected, find the probability that their mean weight is between 120 lb and 161 lb. the probability is approximately? c. when redesigning the ejection seat, which probability is more relevant? . part (b) because the seat performance for a single pilot is more important. b. part (b) because the seat performance for a sample of pilots is more important. c. part (a) because the seat performance for a sample of pilots is more important. d. part (a) because the seat performance for a single pilot is more important.