The table below shows the soft drink preferences of people i

The table below shows the soft drink preferences of people in three age groups.

cola root beer lemon-lime

under 21 years of age 40 25 20

between 21 and 40 35 20 30

over 40 years of age 20 30 35

If one of the 255 subjects is randomly selected, fin the probability that the person drinks root beer given that they are over 40. please show al work.

A) 2\\17 B)2\\5 C) 6\\17 D) none of the above

Solution

a) P( over 40) = 85/255                      
P(person drinks root beer given that over 40) = P( person drinks root beer and over 40) / P( over 40)                      
P( person drinks root beer and over 40) = 30/255                      
P(person drinks root beer given that over 40) = P( person drinks root beer and over 40) / P( over 40) = (30/255)/(85/255) = 30/85 = 6/17