Probability-Selections&Arrangement

**The Question:**

Given a 5x5 Chess-Board (with 25 squares).

On each square, someone writes randomly one of the digits- 0 or 1.

A. What is the probability of that in at least on row, the sum of the digits will be excatly 3?

B.Someone scatters randomly 25 discs on the board. On 10 of the discs, the digit 1 is written and on 15 of the other discs, the digit 0 is written.

What is the probability that the sum of the digits in each and every one of the rows will the same?

I've no idea about these two parts...I'll be delighted to get some guidance

Thanks a lot!