Hello, Ashish!

I got "None of these" until I read the problem again . . .In a room there are 7 persons.

Find the probability that two of them are born on the same day of week.

. .

I believe the problem means "exactlytwo have the same weekday of birth".

There are: . ways to pick the two people.

. . Call them and

can have any day for his birthday:

. . must have the same day: .

. . . . must have one of the remaining six days: .

. . . . . . must have one of the remaining five days: .

. . . . . . . . must have one of the remaining four days: .

. . . . . . . . . . must have one of the remaining three days: .

. . . . . . . . . . . . . must have one of the remaining two days: .

Therefore, the probability is: .

. . which simplifies to: . . . . answer (c)