Eli wrote an article for the school paper on volunteer opportunities in the community. He included these results from a school-wide survey:
19% of the students surveyed volunteer at a food bank.
14% of the students surveyed volunteer at an animal shelter.
22% of the students surveyed volunteer at a food bank or an animal shelter.
What is the probability that a student randomly selected from among those who took the survey volunteers at both a food bank and an animal shelter?
You can construct a Venn diagram, with circles F , for food bank, and A, for animal shelter.
label the intersection of the two circles x
label the F only as 19-x, label the A only part as 14-x
then:
19-x + x + 14-x = 22
x = 11
so prob(a person works at either F OR A) = 11/100