The probability that a randomly selected individual in a certain community has made an online purchase is 0.45. Suppose that a sample of 10 people from the community is selected, what is the probability that at most 3 of them has made an online purchase? Round your answer to 2 decimal places.

1 answer

Find P(0), P(1), P(2), and P(3). Add together for the total probability.

n = 10
x = 0,1,2,3
p = 0.45

Use a binomial probability table or a calculator. It will be easier than doing this by hand.

If you must do this by hand, here is a formula:

P(x) = (nCx)(p^x)[q^(n-x)]

I'll let you take it from here.