The probability that a leap year will have 53 Fridays or 53 Saturdays, is:A.2/7 B.3/7 C.4/7 D.1/7

To solve this problem, let's break it down:

Step 1: Understand the structure of a leap year
A leap year has 366 days, which is equivalent to 52 weeks and 2 extra days (since 366 ÷ 7 = 52 weeks with a remainder of 2 days).

Step 2: Determine the days of the week for a leap year
In a leap year, the two extra days can be:

Sunday and Monday
Monday and Tuesday
Tuesday and Wednesday
Wednesday and Thursday
Thursday and Friday
Friday and Saturday
Saturday and Sunday
These two extra days will determine the distribution of weekdays in the year.

Step 3: Check the conditions for 53 Fridays or 53 Saturdays
In a leap year, every day of the week occurs 52 times. The two extra days will give one additional occurrence of each of the two days they represent.

For example:

If the two extra days are Friday and Saturday, then there will be 53 Fridays and 53 Saturdays.
If the two extra days are Thursday and Friday, there will be 53 Fridays, but not 53 Saturdays.
If the two extra days are Saturday and Sunday, there will be 53 Saturdays, but not 53 Fridays.
Step 4: Find the favorable outcomes
The two extra days can be any pair of consecutive days, and we need to check when these pairs include Friday or Saturday:

(Thursday, Friday) gives 53 Fridays.
(Friday, Saturday) gives 53 Fridays and 53 Saturdays.
(Saturday, Sunday) gives 53 Saturdays.
Thus, there are 3 favorable outcomes out of the 7 possible pairs of extra days.

Step 5: Calculate the probability
The probability is the ratio of favorable outcomes to total possible outcomes:

Probability = (Number of favorable outcomes) / (Total possible outcomes) = 3 / 7

Final Answer:
The probability that a leap year will have 53 Fridays or 53 Saturdays is 3/7.

Therefore, the correct option is B. 3/7.