The probability that a leap year will have 53 Fridays or 53 Saturdays is
In a leap year we have 366 days. So, every day of a week comes 52 times in 364 days.
Now we have 2 days remaining.
These 2 days can be-
S = {MT, TW, WTh, ThF, FSa, SaSu, SuM}
Where S is the sample space.
As there are total 7 possibilities.
∴ n(S) = 7
Let A denote the event of getting 53 Fridays and B denote event of getting 53 Saturdays.
We have to find P(A ∪ B)
Clearly,
P(A) = 2/7
P(B) = 2/7
And P(A ∩ B) = 1/7
∴ P(A ∪ B) = 2/7 + 2/7 – 1/7 = 3/7
As our answer matches only with option (b)
∴ Option (b) is the only correct choice.