SOLUTION: I found this problem on the agebra.com website. I have a few problems like this but cannot figure out how to do them. I just dont want the answer I would like to see it worked out

Algebra ->  Permutations -> SOLUTION: I found this problem on the agebra.com website. I have a few problems like this but cannot figure out how to do them. I just dont want the answer I would like to see it worked out      Log On


   



Question 412692: I found this problem on the agebra.com website. I have a few problems like this but cannot figure out how to do them. I just dont want the answer I would like to see it worked out so I know how to do my other problems. Any help would be so greatly appreciated.
In a shipment of 50 transformers, 7 are known to be defective. If 30 transformers are picked at random, what is the probability that all 30 are nondefective? Assume that all transformers look alike and have an equal probability of being chosen.
Thanks,
Dave

Answer by sudhanshu_kmr(1152) About Me  (Show Source):
You can put this solution on YOUR website!
total no.= 50, defective = 7 , non-defective = 43

no. of ways to select 30 transformers from total 50= 50C30 ......i.e n(S)
no. of ways to select 30 transformers for 43(non-defective)= 43C30 .....i.e n(A)

probability that all are non-defective P(A)= n(A)/n(S)= 43C30 / 50C30