A salesperson contacts eight potential customers per day. From past experience, we know that the probability of a potentail customer making a purchase is 0.10.

Question

a) What is the probability the salesperson will make at least two sales in a day?
-Do you use binomial formula for this question, the answer i got is 0.1869, am i correct?

b) What percentage of days will the salesperson not make a sale?

c) What is the expected number of sales per day?

a) Yes, use the binomial formula and calculate 1 - P(0) - P(1).
I get 1 - 0.4305 + 0.3826 = 0.1869
Congratulations
b) That would be P(0). Use the binomial formula again. I get 43.05%
c) The expected numnber of sales is
8* 0.1 = 0.8.

For a shortcut, use this site:
http://www.ciphersbyritter.com/JAVASCRP/BINOMPOI.HTM#Binomial

but for b) it is asking what percentage of days will the salesperson not make a sale, not what is the probability the salesperson will not make a sale in a day. These are two different questions right, or did i just misunderstood the question?

Answer 1

Yes, you are correct. The question is asking for the percentage of days that the salesperson will not make a sale. To calculate this, you need to use the binomial formula to calculate the probability of not making a sale in a day, and then convert that probability to a percentage.