An unbiased coin is tossed four times. Find the probability of the given event. The coin lands heads more than once.

Question

The answer has to be rounded to 4 decimal places.

Answer 1

There are 16 possible results in 4 tosses of the coin:

HHHH, HHHT, HHTH, HHTT

HTHH, HTHT, HTTH, HTTT

THHH, THHT, THTH, THTT

TTHH, TTHT, TTTH, TTTT

From this we can see that one head or fewer occurs in just 5 cases: HTTT, THTT, TTHT, TTTH, TTTT. That means that in the remaining 11 cases heads occurs more than once, giving us the probability of 11/16=0.6875.