Answer
$P(fewer~than~19)=0.9308$
If we randomly select 20 married people 10,000 times, we would expect about 9308 trials result in fewer than 19 of 20 married people that hide purchases from their mates.
Work Step by Step
The probability that fewer than 19 of 20 married people hide purchases from their mates is the complement of the probability that at least 19 of 20 married people hide purchases from their mates.
Using the Complement Rule (see page 275):
$P(fewer~than~19)=P(X\lt19)=1-P(at~least~19)=1-0.0692=0.9308$
