question_answer

Box contains 2 one rupee, 2 five rupee, 2 ten rupee and 2 twenty rupee coin. Two coins are drawn at random simultaneously. The probability that their sum is Rs. 20 or more, is

A)  1/4                       

B)  1/2

C)  3/4                       

D)  1/8

Correct Answer: B

Solution :

 Let A be the event such that sum is Rs. 20 or more \[\therefore \]P(l) = l-P (Total value is < 20)         \[=1-\frac{^{6}{{C}_{2}}{{-}^{2}}{{C}_{2}}}{^{8}{{C}_{2}}}=1-\frac{14}{28}=1-\frac{1}{2}=\frac{1}{2}\]