You have a plate of 50 cookies. Ten have chocolate chips and 14 have pecans. Of the cookies mentioned in the preceding sentence, 5 have both chocolate chips and pecans. You select a cookie at random.

Question

You have a plate of 50 cookies. Ten have chocolate chips and 14 have pecans. Of the cookies mentioned in the preceding sentence, 5 have both chocolate chips and pecans. You select a cookie at random. What is the probability that your cookie has chocolate chips or pecans?

P(chocolate chips or pecans) = 

Answer 1

10 cookies have chocolate chips and 14 have pecans. If 5 cookies have both pecans and chocolate chips, then we know that 10-5=5 cookies have only chocolate chips and 14-5=9 cookies have only pecans. So this means that 5 + 5 + 9 = 19 cookies have either chocolate chips or pecans or both.

19/50 = 38/100.

There is a 38% chance your cookie has either chocolate chips or pecans.