Hello AllengeThis is an example of a Binomial Distribution. The probability of 'success' (that a given teenage woman chosen at random would get pregnant in their teenage years), is denoted by . The probability of 'failure' (that she would not), is denoted by . If the experiment (choosing and interviewing a teenage woman at random) is repeated times, then the probability of successes and failures is:

So you need to put .

(I think the answer is 0.366 (3 d.p.)

Grandad