Binomial Probability

Question

A box of parts has 8 working and 4 defective parts. If 2 parts are selected at random, what is the probability that no defective parts are selected?

Answer 1

Hi Melissa,

 

I am assuming this is without replacement.

For the first part selected, the possibility of it being good is 8/12=2/3.

For the second part selected, the possibility of it being good is 7/11.

The final possibility is the product of these two possibilities. 2/3*7/11 = 14/33