A particular telephone number is used to receive both voice

A particular telephone number is used to receive both voice calls and fax messages. Suppose that 25% of the incoming calls involve fax messages, and consider a sample of incoming calls. What is the probability that at most 4 of the calls involve a fax message? What is the probability that exactly 4 of the calls involve a fax message? What is the probability that at least 4 of the calls involve a fax message? What is the probability that more than 4 of the calls involve a fax message? You may need to use the appropriate table in the Appendix of Tables to answer this question.

Solution

P=0.25

n =25

this is bionomial distribution

a)P(x<=7) = 0.7265

b) P(x=7) = 0.165

c) P(x>=7) = 0.4389

d)P(x>7) = 0.2734