Thread: Probability Distrabution

Find the probability of getting at least three defective items in a batch of ten items if the overall percentage of defects is 40%.

Ok, so this is my question "at least 3" so i am using my TI-84 plus clac. and i make a table by using binompdf(n,p) and putting it in list 1.

It gives me this
0-.00605
1-.04031
2-.12093
3-.21499
4-.25082
5-.20066
6-.11148
7-.04247
8-.01062
9-.000157
10-1E-4

so if i want to know the probablity of at least 3 what do i do with these numbers?

p(at least 3) = p(3) + p(4) + p(5) + ... -- Jut add them up.

Of course, it is often easier to think about what you don't want.

p(at least 3) = 1 - p(less than 3) = 1 - (p(0) + p(1) + p(2))

oh duhhh! haha thanks