Sixty percent of the customers of a fast food chain order the Whopper, French fries and a drink. If a random sample of 15 cash register receipts is selected, what is the probability that 10 or more will show that the above three food items were ordered?
A) 1,000
B) 0.186
C) 0.403
D) 0.000

Question

Quizplus · Accepted Answer

This is a binomial probability problem with n=15, p=0.6 and we need to find P(X≥10). Using binomial probability formula, P(X≥10) = 1 - P(X<10) = 1- ∑_(i=0)^(i=9) (15Ci)(0.6)^i(0.4)^(15-i).

Using calculator or statistical tables, we find this probability to be approximately 0.403. Therefore, the correct choice is C.

Sixty Percent of the Customers of a Fast Food Chain