Four fair coins are tossed simultaneously. The probability that at least one head and one tail turn up is:

A. 1/16
B. 1...

Question

Four fair coins are tossed simultaneously. The probability that at least one head and one tail turn up is:

A. 1/16
B. 1/4
C. 7/8
D. 15/16

Accepted Answer

P(at least one head and at least one tail) = 7/8. When four fair coins are tossed, the complementary event to getting at least one head and at least one tail is getting all heads or all tails. Using the complement rule, we subtract both extreme outcomes from 1. There are 2^4 = 16 equally likely outcomes, of which only HHHH and TTTT fail the condition. So the probability is 1 - 2/16 = 14/16 = 7/8.

Four fair coins are tossed simultaneously. The probability that at least one head and one tail turn up is: A. 1/16 B. 1/4 C. 7/8 D. 15/16