Question

In a certain group of 15 students, 5 have graphics calculators and 3 have a computer at home (one student has both). Two of the students drive themselves to college each day and neither of them has a graphics calculator nor a computer at home. A student is selected at random from the group.Find the probability that the student either drives to college or has a graphics calculator.

Answer 1

A = set of students having computer , n(A) = 3

B = set of students having graphic calculator , n(B) = 5

C = set of students students who drive themselves to college each day , n(C) = 2

n(A⋂B) = 1

n(B or C)=$n(B \bigcup C)$ = 5 + 2 = 7

n(S) = 15

Required probability =$\dfrac{n(B⋃C)}{n(S)}$ = $\dfrac{7}{15}$

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