Question

The probability that ${13}^{\text{th}}$ day of a randomly chosen month is a Friday is

• A. $\frac{1}{7}$
• B. $\frac{1}{84}$
• C. $\frac{1}{12}$
• D. $\frac{1}{42}$

Answer 1

The correct option is B $\frac{1}{84}$

Probability of choosing any month out of $12$ months $=\frac{1}{12}.$
${13}^{\text{th}}$ day can be any day out of $7$ days.
Probability that it will be Friday $=\frac{1}{7}.$
$\therefore$ Required probability $=\frac{1}{12}\times \frac{1}{7}=\frac{1}{84}$