Question

In a group of 25 students at lunch, 10 prefer ketchup on their hamburger, 10 prefer mustard on

their hamburger, and 5 like both ketchup and mustard on their hamburger. The rest of the
students in the group prefer neither. What is the probability that a student selected from this
group will prefer ketchup or mustard on their hamburger?

Answer 1

15/25 or 3/5 or 60%

Explanation:

P(K or M) = P(K) + P(M) - P(K and M)

=
`(10)/(25)` +
`(10)/(25)` -
`(5)/(25)`

=
`(15)/(25)`

= .6 or 60%