posted by smartypants .
please help cuz i been trying for ages and cant get the answer
each telephone call made to the emergency services either is or is not legitimate. suppose that each call received has probability 0.02 that it is not legitimate. assume that the legitimacy of one call is independent of whether or not other calls are legitimate.
(the choices of answers are at the bottom of the page)
QU1) whats the closet option that they receive at least 100calls before they receive one which is not legitimate?
qu2) whats the closet option that in 150calls at least one is not legitimate?
the choices of answers are:
Q1) probability of exactly 100 consecutive "good" calls = (0.98)^100 = 0.133
That satisfies the "at least 100" criterion.
Q2)The probability that all of 150 calls are legitimate is (0.98)^150 = 0.048. One minues that, or 0.952, is the probability that at least one is NOT legitimate.