1. When local calls are made in NYC, 60% go through on the first try, and the rest get a busy signal. (We assume there is no third possibility).

Let X=# times a call is actually placed for the call to go through

Of course on each try, the call goes through with probability .6.

a. Identify the distribution of X—name and parameter(s). Explain your choice. What is

P[X>1].

b. How many calls do you expect to have to place in order to get through 5 times? First identify the distribution of the # of calls required to get through 5 different times.

c. Let X=total # of calls that get a busy line when 10 different numbers are attempted, once each.

i. What is the distribution of X

ii. What is P[ X >2 ] ?