In how many ways 3 mathematics books, 4 history books, 3 chemistry books and 2 biology books can be arranged on a shelf so that all books of the same subjects are together

A student has to answer 10 questions, choosing atleast 4 from each of Parts A and B. If there are 6 questions in Part A and 7 in Part B, in how  many ways can the student choose 10 questions?

Three married couples are to be seated in a row having six seats in a cinema hall. If spouses are to be seated next to each other, in how many ways can they be seated? Find also the number of ways of their seating if all the ladies sit together.

 In a small village, there are 87 families, of which 52 families have atmost 2 children. In a rural development programme 20 families are to be chosen for assistance, of which atleast 18 families must have at most 2 children. In how many ways can the choice be made?

A boy has 3 library tickets and 8 books of his interest in the library. Of
these 8, he does not want to borrow Mathematics Part II, unless Mathematics Part I is also borrowed. In how many ways can he choose the three books to be borrowed?

Find the number of permutations of n different things taken r at a time
such that two specific things occur together.

There are four bus routes between A and B; and three bus routes
between B and C. A man can travel round-trip in number of ways by bus from A to C via B. If he does not want to use a bus route more than once, in how many ways can he make round trip?
(A) 72
(B) 144
(C) 14
(D) 19

In how many ways a committee consisting of 3 men and 2 women, can be chosen from 7 men and 5 women?
(A) 45
(B) 350
(C) 4200
(D) 230

All the letters of the word ‘EAMCOT’ are arranged in different possible
ways. The number of such arrangements in which no two vowels are adjacent to each  other is
(A) 360
(B) 144
(C) 72
(D) 54

 Ten different letters of alphabet are given. Words with five letters are
formed from these given letters. Then the number of words which have atleast one letter repeated is
(A) 69760
(B) 30240
(C) 99748
(D) 99784

The number of signals that can be sent by 6 flags of different colours
taking one or more at a time is
(A) 63
(B) 1956
(C) 720
(D) 21