MCQ
The probability that a leap year selected at random contains either $53$ Sundays or $53 $ Mondays, is
- A$\frac{2}{7}$
- B$\frac{4}{7}$
- ✓$\frac{3}{7}$
- D$\frac{1}{7}$
There are $7$ possibilities for these $2$ extra days viz.
$(i)$ Sunday, Monday, $(ii)$ Monday, Tuesday,
$(iii)$ Tuesday, Wednesday, $(iv)$ Wednesday, Thursday,
$(v)$ Thursday, Friday, $(vi)$ Friday, Saturday and
$(vii)$ Saturday, Sunday.
Let us consider two events :
$A:$ the leap year contains $53$ Sundays
$B:$ the leap year contains $53$ Mondays.
Then we have $P(A) = \frac{2}{7},\,\,P(B) = \frac{2}{7},\,\,P(A \cap B) = \frac{1}{7}$
$\therefore $ Required probability $ = P(A \cup B)$
$ = P(A) + P(B) - P(A \cap B) = \frac{2}{7} + \frac{2}{7} - \frac{1}{7} = \frac{3}{7}.$
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.