Answer:
1/16,807 chance that they all will be born on Friday
Probably 5/7, but don't take my word for it.
Step-by-step explanation:
There are 7 days of the week.
There is a 1/7 chance for one kid to be born on a certain day of the week.
We can attach an exponent of 5 since the 1/7 is a constant, and I'm not going to bother typing the same thing over and over again.
(1/7)^5 = 1/16,807.
The probability of all of them being born on Friday or anyday is 1/16,807.
The probability of each person being born on a different day of the week is probabily going to be 5/7, but it could be different, because you need to factor in the requirement that they are not born on the same day.
I can guarantee that the first question is probably correct, but not the second.
