A shipment of 8 television sets contains 2 black-and-white sets and 6color sets. If 2 television sets are to be chosen at random from this shipment, what is the probability that at least 1 of the 2 sets chosen will be a black-and-white set?
A. 1/7 B. ¼ C. 5/14 D. 11/28 E. 13/26
The way i tried to solve this is - it says atleast 1 B&W so you can calculate prob for getting 1 B&W and 2 B&W.
2/8 * 6/7 + 2/8 * 1/7 = 1/4 but the answer key says E.
Please show your method.
I believe you miss something in your calculation.
Using your method
Prob[B&W >= 1] = Prob[B and W] + Prob[B and B]
= (2C1)x(2/8)x(6/7) + (2/8)x(1/7)
= 3/7 + 2/56 = (24+2)/56 = 13/28
You miss (2C1) in your calculation.