If a+b+c = 21, what is the total number of non - negative integral solutions?

Correct Answer: 1587600

Explanation:

 H   L   C   N    T    A   U   I   O

 

      L        N          A        I

 

There are total 131 letters out of which 7 are consonants and 6 are vowels. Also ther are 2L's , 2N's, 2A's and 2I's.

 

If all the consonants  are together then the numberof arrangements =  7 ! 2 !x 1/2! .

But the 7 consonants  can be arranged themselves in   7 ! 2 ! x 1/2! ways. 

 

Hence the required number of ways =  7 ! 2 ! 2 ! 2 = 1587600

Correct Answer: 21600

Explanation:

4 novels can be selected out of 5 in  5 C 4 ways.

2 biographies can be selected out of 4 in  4 C 2 ways.

Number of ways of arranging novels and biographies = 5 C 4 * 4 C 2  = 30

After selecting any 6 books (4 novels and 2 biographies) in one of the 30 ways, they can be arranged on the shelf in 6! = 720 ways.

By the Counting Principle, the total number of arrangements = 30 x 720 = 21600

Correct Answer: 720

Explanation:

There are 7 letters in the word ?Bengali of these 3 are vowels and 4 consonants.

 

Considering vowels a, e, i as one letter, we can arrange 4+1 letters in 5! ways in each of which vowels are together. These 3 vowels can be arranged among themselves in 3! ways.

 

Total number of words = 5! x 3!= 120 x 6 = 720

Correct Answer: 360

Explanation:

CAPITAL = 7

 

Vowels = 3 (A, I, A)

 

Consonants = (C, P, T, L)

 

5 letters which can be arranged in   5 P 5 = 5 !

 

Vowels A,I =  3 ! 2 !

 

No.of arrangements = 5! x  3 ! 2 !=360

Correct Answer: 10!/2

Explanation:

As A1 speaks always after A2, they can speak only in  1st  to 9th places and 

 

A2 can speak in 2nd to 10 the places only when A1 speaks in 1st place 

 

A2 can speak in 9 places the remaining 

 

 A3, A4, A5,...A10  has no restriction. So, they can speak in 9.8! ways. i.e

 

when A2 speaks in the first place, the number of ways they can speak is 9.8!.

 

When A2 speaks in second place, the number of ways they can speak is  8.8!.

 

When A2 speaks in third place, the number of ways they can speak is  7.8!. When A2 speaks in the ninth place, the number of ways they can speak is 1.8!

 

 

 

Therefore,Total Number of ways they can  speak = (9+8+7+6+5+4+3+2+1) 8! =  9 2 ( 9 + 1 ) 8 ! = 10!/2

Correct Answer: 325

Explanation:

Required number of signals =  5 P 1 + 5 P 2 + 5 P 3 + 5 P 4 + 5 P 5

= 5 + 20 + 60 + 120 + 120 = 325

 

 

Correct Answer: 253

Explanation:

The first person shakes hands with 22 different people, the second person also shakes hands with 22 different people, but one of those handshakes was counted in the 22 for the first person, so the second person actually shakes hands with 21 new people. The third person, 20 people, and so on...
So,
22 + 21 + 20 + 19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1
= n(n+1)/2 = 22 x 23 /2 = 11 x 23 = 253.

Correct Answer: 125

Explanation:

Methods for selecting 4 questions out of 5 in the first section = 5 x 4 x 3 x 2 x 1/4 x 3 x 2 x 1 = 5. Similarly for other 2 sections also i.e 5 and 5

So total methods = 5 x 5 x 5 = 125.

Correct Answer: 36

Explanation:

Given there are 9 flavours of ice creams.

 

Each child takes the combination of two flavours and no two children will have the same combination

 

This can be done by  ways i.e children.

 

Number of children= C 2 9  = 9 x 8 / 1x 2 = 36.

Correct Answer: 243

Explanation:

Digits are 0,1,2,3,4,5,6,7,8,9. So no. of digits are 10

 

First all possible case => 9(0 excluded) x 10 x 10 = 900

 

Second no repetition allowed =>9 x 9 x 8 = 648

 

Third all digits are same => 9 (111,222,333,444,555,666,777,888,999)

 

Three digit numbers where two of the three digits are same = 900 - 648 - 9 = 243 ;