Answer:
a) 23.11% probability of making exactly four sales.
b) 1.38% probability of making no sales.
c) 16.78% probability of making exactly two sales.
d) The mean number of sales in the two-hour period is 3.6.
Step-by-step explanation:
For each phone call, there are only two possible outcomes. Either a sale is made, or it is not. The probability of a sale being made in a call is independent from other calls. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.
In which 
is the number of different combinations of x objects from a set of n elements, given by the following formula.
And p is the probability of X happening.
A telemarketer makes six phone calls per hour and is able to make a sale on 30% of these contacts. During the next two hours, find:
Six calls per hour, 2 hours. So
Sale on 30% of these calls, so 
a. The probability of making exactly four sales.
This is P(X = 4).
23.11% probability of making exactly four sales.
b. The probability of making no sales.
This is P(X = 0).
1.38% probability of making no sales.
c. The probability of making exactly two sales.
This is P(X = 2).
16.78% probability of making exactly two sales.
d. The mean number of sales in the two-hour period.
The mean of the binomia distribution is
So
The mean number of sales in the two-hour period is 3.6.
