You have a plate of 50 cookies. Ten have chocolate chips and 15 have pecans. Of the cookies mentioned in the preceding sentence, 4 have both chocolate chips and pecans. You select a cookie at random. What is the probability that your cookie has chocolate chips or pecans?

First find the total amount of cookies with chocolate chips and pecans. Since there is 4 that has both you need to subtract 4 from 15 which leaves you with 11 cookies that just has pecans. Next subtract 4 from 10 which leaves you with 6 cookies with just chocolate chip. So the total number of cookies with chocolate chips or pecans is 21. So to find the probability all you need to do is divide the number of cookies with pecans or chocolate chips by the total number of cookies and then multiply by 100 to get the percent. (21/50)•100 = 42% or a 21/50 chance