A box contains 10 ​transistors,4 of which are defective. If 4 are selected at​ random, find the probability that

Question

a. All are defective.
b. None are defective.

Answer 1

first one:
4/10
second one
3/9
third one
2/8
fourth one
1/7
now multiply :)
------------------------
ow all good
first one
6/10
second one
5/9
etc