Seventy percent of the light aircraft that disappear while

Answer : Step 1 : Given Seventy percent of the light aircraft that disappear while in flight in a certain country are subsequently discovered. Of the aircraft that are discovered, 60% have an emergency locator, whereas 90% of the aircraft not discovered do not have such a locator. Suppose a light aircraft has disappeared. a). 60% of 70% are discovered and have a locator.This is 42% of all aircraft that disappear. 40% of 70% are discovered and do not have a locator. This is 28% of all aircraft that disappear. 10% of 30% are not discovered but do have a locator. This is 3% of all aircraft that disappear. 90% of 30% are not discovered and do not have a locator. This is 27% of all aircraft that disappear. The table is given below. Locator Has Hasn't Total Discovered 42 28 70 Not discovered 3 27 30 Total 45 55 The numbers were filled as follows: I assumed the total number of light aircraft disappeared to be 100 70% of them (70) are discovered. So 30 are not discovered. 60% of the 70 discovered aircraft (42) have a locator. So 28 don't have it. 90% of those not located have not a locator (27) so 3 have one. The totals on the last line are just that. Let the probability that it will not be discovered. Total number of aircraft that do have a locator : 42 + 3 = 45 Number of aircraft that do have a locator but are not discovered, divided by total number of aircraft that have a locator : 3 45 45 have an emergency locator and 3 of them are not discovered, so the probability is 3/45 = 1/15 Therefore the probability that it will not be discovered is 1/15 .