MCQ
The probability that a leap year will have $53$ Fridays or $53$ Saturdays is:
  • A
    $\frac{2}{7}$
  • $\frac{3}{7}$
  • C
    $\frac{4}{7}$
  • D
    $\frac{1}{7}$

Answer

Correct option: B.
$\frac{3}{7}$
We know that a leap year has $366$ days $($i.e. $7 \times 52 + 2) = 52$ weeks and $2$ extra days .
The sample space for these $2$ extra days is given below:
$S = \{($Sunday, Monday$), ($Monday, Tuesday$), ($Tuesday, Wednesday$), ($Wednesday, Thursday$), ($Thursday, Friday$), ($Friday, Saturday$), ($Saturday, Sunday$)\}$ There are $7$ cases.
$\therefore\text{n(S)}=7$
Let $E$ be the event that the leap year has $53$ Fridays or $53$ Saturdays.
$E = \{($Thursday, Friday$), ($Friday, Saturday$), ($Saturday, Sunday$)\}$
i.e. $n(E) = 3$
$\therefore \text{P(E)}=\frac{\text{n(E)}}{\text{n(S)}}=\frac{3}{7}$
Hence, the probability that a leap year has $53$ Fridays or $53$ Saturdays is $\frac{3}{7}$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free