Of the 102 customers at a restaurant 35 ate french fries and 55 ate hamburgers. Of these customers, 14 ate both. Find the probability that a customer chosen at random ate french fries given that they ate a hamburger
There are 55+14=69 customers that ate hamburguers: the ones that only ate hamburguers (55) and the ones who ate both hamburguers and fries.
Given that the customers ate hamburguers, the probability that they ate fries too is [tex]\frac{14}{69} =20.29\%[/tex].
This is because once you know that the customers ate hamburguers, you are analisying a portion of the data: the one that fulfill the requirement of eating hamburguers. Then, looking inside of the group that ate hamburguers, 20.3% of the group ate both hamburguers and fries (14/69), and the rest (79.7%) only ate hamburguers.
The probability of choosing randomly an individual who ate both things is then 20.3%.
