The sum of the digits at the 10^{th}
place of all numbers formed with the help of 2, 4, 5, 7 taken all at a time is

**A. ** 432

**B. ** 108

**C. ** 36

**D. ** 18

**Answer : ****Option B**

**Explaination / Solution: **

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In an examination there are three multiple choice questions and each question has 5 choices .
Number of ways in which a student can fail to get all answer correct is

**A. ** 125

**B. ** 124

**C. ** 64

**D. ** 63

**Answer : ****Option B**

**Explaination / Solution: **

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The number of ways in which the following prize be given to a class of 30 boys first and second in mathematics, first and second in physics, first in chemistry and first in English is

**A. ** 30^{4} x 29^{2}

**B. ** 30^{3} x 29^{3}

**C. ** 30^{2} x 29^{4}

**D. ** 30 x 29^{5}

**Answer : ****Option A**

**Explaination / Solution: **

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The number of 5 digit numbers all digits of which are odd is

**A. ** 25

**B. ** 5^{5}

**C. ** 5^{6}

**D. ** 625

**Answer : ****Option B**

**Explaination / Solution: **

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In 3 fingers, the number of ways four rings can be worn is ………..ways.

**A. ** 4^{3} - 1

**B. ** 3^{4}

**C. ** 68

**D. ** 64

**Answer : ****Option D**

**Explaination / Solution: **

4 rings can be worn in 3 fingers in 34 ways

4 rings can be worn in 3 fingers in 34 ways

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If ^{(n+5)}P_{(n+1)} = ( 11(n-1) /2 )^{(n+3)}P_{n}, then the value of n are

**A. ** 7 and 11

**B. ** 6 and 7

**C. ** 2 and 11

**D. ** 2 and 6

**Answer : ****Option B**

**Explaination / Solution: **

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The product of r consecutive positive integers is divisible by

**A. ** r!

**B. ** (r - 1)!

**C. ** (r + 1)!

**D. ** r^{r}

**Answer : ****Option A**

**Explaination / Solution: **

Product of*r* consecutive positive integers is divisible by r! (theorem)

Product of

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The number of five digit telephone numbers having at least one of their digits repeated is

**A. ** 90000

**B. ** 10000

**C. ** 30240

**D. ** 69760

**Answer : ****Option D**

**Explaination / Solution: **

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If a^{2}-^{a}C_{2} = ^{a2}-^{a} C_{4} then the value of ’a’ is

**A. ** 2

**B. ** 3

**C. ** 4

**D. ** 5

**Answer : ****Option B**

**Explaination / Solution: **

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There are 10 points in a plane and 4 of them are collinear. The number of straight lines joining any two points is

**A. ** 45

**B. ** 40

**C. ** 39

**D. ** 38

**Answer : ****Option B**

**Explaination / Solution: **

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