Question

Find the probability that a leap year will have 53 Fridays or 53 Saturdays.

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

There are 366 days in a leap year, in which there are 52 weeks and 2 days. The combination of 2 days can be
Sunday – Monday
Monday – Tuesday
Tuesday – Wednesday
Wednesday – Thursday
Thursday – Friday
Friday – Saturday
Saturday – Sunday
P (53 Fridays) =$\frac{2}{7}$;P(53 Saturdays) = $\frac{2}{7}$
P (53 Fridays and 53 Saturdays) = $\frac{1}{7}$
$\therefore$ P(53 Fridays or Saturdays)
= P(53 Fridays) + P(53 Saturdays)
– P(53 Fridays or Saturdays)
$=\frac{2}{7}+\frac{2}{7}-\frac{1}{7}=\frac{3}{7}$