Question

A teacher surveyed her class about their

online accounts and wanted to know if they
had a Tablet Device or if they had a Smart
Phone. She wanted to know for a lab she
was going to have in class. The Venn
diagram shows her results. If a person from
the class is randomly selected, what is the
probability that the person has a Smart
Phone but not a tablet?

Answer 1

`(2)/(5)`

Explanation:

From the Venn diagram we can deduce the following:

• The number of students having only tablet is 3.
• The number of students having only smart phone is 8.
• The number of students having both is 5.

• The number of students having neither is 4.

• Total number of students in class is 3+8+5+4=20.

Probability that a student has a smartphone but not a tablet =
`(Number\ of\ students\ having\ only\ tablet)/(Total\ number\ of\ students)` =
`(8)/(20) = (2)/(5)`.