Question 412692
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