The proportion of defectives in a mass produced item is 5%
What is the probability that a random sample of 10 of these items will
contain at most 2 defectives?

This is just like the previous problem, except the 'at most' means
that you have to add the probabilities of getting 0 defectives, 1
defective, and 2 defectives.

Again, the general formula is
nCx*(p^x)*[(1-p)^(n-x)]  I'll leave x blank since we'll be plugging in
3 different values for it.

10Cx*(.05^x)*[(.95^(10-x)]

At x=0, this gives: .5987
At x=1, this gives: .3151
And, as we saw earlier, at x=2: .0746

The sum is then: .9884 = 98.84%

Hope this helps!

It helps heaps - I didnt know I had to add them.
thanks so much for your help.