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February 13, 2016
Posted by **Jane** on Friday, March 16, 2012 at 1:57pm.

a. At least 3 have been attacked

b. No more than 5 have been attacked

c. less than 15 have been attacked

- statistics -
**MathGuru**, Friday, March 16, 2012 at 6:18pmThe 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.