请教两道统计题.那位高手能解答一下.

louis_921

An important part of customer service responsibilities of a natural gas utility company concerns the speed with which calls relating to no heat in a house can be serviced,suppose that one service variable of importance refers to whether

or not the repair person reaches the home within a two hour period.past data indicate that the likelihood is 0.6 that the repair person reachs the home within a two-hour period.

if a sample of five service calls for (no heat) is selected,what is the probability that the repair person will arrive at:

a).Two houses within a two-hour period?

b)more than two houses within a two-hour period?

C)at least one house and less than four houses within the two-hour period?

if a sample of twelve service calls for (no heat) is selected:

what is the probability that the repair person will arrive at three houses within a two hour period?