In a large survey, it was discovered that 1 out of every 5 adults visits Disney World every year. If 30 adults are randomly selected what is the probability that exactly 7 of them will visit Disney World this year?

The answer is .154. I do not understand how answer was gotten.

It is a binomial probability.

It was gotten like so:

C(30,7)(.20)^{7}(.80)^{23}=.1538...

Where C(30,7) is the number of ways to choose 7 items from 30