Question

The probability that it is Friday and that a student is absent is 0.03. Since there are 5 school days in a week, the probability that it is Friday is 0.2. What is the probability that a student is absent given that today is Friday?

• A. $\frac{15}{100}$
• B. $\frac{87}{100}$
• C. $\frac{49}{50}$
• D. $\frac{11}{100}$
• E. None of these

Answer 1

The correct option is A $\frac{15}{100}$

$P(B\mid A)$ = $\frac{P(A\cap B)}{P\left(A\right)}$
$P(Absent\mid Present)$ = $\frac{P\left(absentandfriday\right)}{P\left(friday\right)}$
= $\frac{0.03}{0.2}$
= 0.15
= 15%