Mcq help needed

can pl help me out how answer of 4,8 and 10 problem

Please paste the questions here.

From the set of numbers s={1, 2, 3, 4}, how many minimum numbers must be selected to guarantee that at least one pair of these numbers has a sum equal to 7?

In how many ways 5 men and 3 women can sit together on a circle such that a particular men m1 and particular women w1 never sit adjacent to each other?

Let x = a5 + b11 , where a>0 and b>0. What is the largest value of x that can not be made?

Ques 4 is based on Pigeonhole Principle. Please study about it and then you will be able to solve.
Q8 is based on circular permutation i.e 7!-6! You can refer this https://math.stackexchange.com/questions/1305844/seating-arrangements-of-four-men-and-three-women-around-a-circular-table/1305930
Your last question is not clear enough. Please share its screenshot.

pl explain 4 th problem…From the set of numbers s={1, 2, 3, 4}, how many minimum numbers must be selected to guarantee that at least one pair of these numbers has a sum equal to 7?.