PROBABILITY A2

When a coin is tossed twice, find the probability of having at least one head.

Solution

From the tree diagram,

n(E) = 3, n(S) = 4

P(E)  =  n(E)

             n(S)

P(E)  =  3

             4

Hence the probability that there are 2 boys and 1 girl is ³/4.