Posted by Jane on Friday, March 16, 2012 at 1:57pm.
The easiest way to do this problem is to use a binomial distribution table.
For a), n = 20, p = .4, x = 0, 1, 2
Add together the probabilities you find in the table, then subtract from 1 for your answer.
For b), n = 20, p = .4, x = 0, 1, 2, 3, 4, 5
Add together the probabilities you find in the table. This will be your answer.
For c), n = 20, p = .4, x = 15, 16, 17, 18, 19, 20
Add together the probabilities you find in the table, then subtract from 1 for your answer.
I hope this helps.