An important part of the customer service responsibilities o

An important part of the customer service responsibilities of a cable company relates to the speed with which trouble in service can be repaired. Historically, the data show that the probability is 0.30 that troubles in a residential service can be repaired on the same day. For the first fifteen troubles reported on a given day, what is the probability that 7 or more troubles will be repaired on the same day

Solution

P(X<2) = 5C0*0.75^5 +5C1*(0.25)*(0.75)^4=0.0156