The breakup about 192 shoppers can be worked out as follows:

Those who did not shop at M =93

Those who shopped at M = 192-93

= 99

Those who had seen the Ad but did not shop at M = 60

Those who did not see the Ad and also did not shop at M= 93-60

= 33

Total number of those who saw the Ad =81

Thus those who saw the add and shopped at M= 81-60

=21

Those who did not see the Ad but shopped at M= 99-21

=78

Probability of a random shopper who saw the Ad and also shopped at M= 21/192

=7/64

=0.11 approx. Ans