Question 1

2880, 480, 92, 24, 8, 4, 2?

Accepted Answer

Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number. Clearly, 92 is wrong.

Question 2

3, 7, 15, 27, 63, 127, 255?

Accepted Answer

Go on multiplying the number by 2 and adding 1 to it to get the next number. So, 27 is wrong.

Question 3

7, 8, 18, 57, 228, 1165, 6996?

Accepted Answer

Let the given number be A, B, C, D, E, F, G. Then A x 1 + 1, B x 2 + 2, C x 3 + 3, D x 4 + 4, E x 5 + 5, F x 6 + 6 are the required number . Clearly, 228 is wrong.

Question 4

Find out the wrong number in the series 125, 106, 88, 76, 65, 58, 53?

Accepted Answer

Go on subtracting prime numbers 19, 17, 13, 11, 7, 5 from the number to get the next number. So, 88 is wrong.

Question 5

1, 5, 14, 30, 50, 55, 91?

Accepted Answer

The pattern is 12 , 12 + 22, 12 + 22 + 32, 12 + 22 + 32 + 42, 12 + 22 + 32 + 42 + 52, 12 + 22 + 32 + 42 + 52 + 62 . But 50 is not of this pattern.

Question 6

Find out the next term in the series 7, 11, 13, 17, 19, ...

Accepted Answer

Given series is a consecutive prime number series. Therefore, the next term will be 23.

Question 7

Find the missing term 6,?, 21, 33, 48

Accepted Answer

Series Pattern +6, +9, +12, +15.... ∴ Missing term = 6 + 6 = 12

Question 8

Find the value of the expression 1 - 2 + 3 - 4 + 5 - 6 + 7 + .... upto 100 terms .?

Accepted Answer

(1 - 2) = -1 (3 - 4) = -1 (5 - 6) = -1 and so on. ∴ Total terms of -1 will be 50. ∴ Answer = -1 x 50 = -50

Question 9

If A represents the arithmetic mean, H represents the harmonic mean and G represents the geometric mean, then what is the relation between them?

Accepted Answer

A = (a + b)/2, 1/H = (1/a + 1/b)/2 ⇒ H = 2ab/(a +b), G = √ab ∴ A x H = {(a + b)/2} x {2ab/(a + b)} = ab = G2 ∴ A x H = G2

Question 10

4, 12, 36,?, 324, 972

Accepted Answer

Series pattern Every next element = 3 x previous element ∴ Missing term = 3 x 36 = 108

Question 11

...., 9, 25, 49, 81, 121?

Accepted Answer

Series pattern 12, 32, 52, 72, 92, 112 ∴ Missing term = 12 = 1

Question 12

12, 15, 21, 30, 42, 57,?

Accepted Answer

Series pattern +3, +6, +9, +12, +15, +18 ∴ Missing term = 57 + 18 = 75

Question 13

3, 5, 9, 17, 33, 65,?

Accepted Answer

Series pattern (2 x Previous element) - 1 ∴ Missing term = (2 x 65) - 1 = 130 - 1 = 129

Question 14

48, 23,?, 4.25, 1.125?

Accepted Answer

Series pattern = (Previous element/2) - 1 Missing term = 23/2 - 1 = 10.5

Question 15

4, 25, 130,?, 3280

Accepted Answer

Series pattern = (5 x Previous element) + 5 ∴ Missing term = (5 x 130) + 5 = 655

Question 16

1, 9, 25, 49, 81,?

Accepted Answer

Series pattern 12, 32, 52, 72, 92, 112 So missing term = 112 = 121

Question 17

2, 15, 41, 80,132,?

Accepted Answer

Series pattern + 13, + 26, + 39, + 52, + 65 ∴ Missing term = 132 + 65 = 197

Question 18

1220, 244, ....., 9.76, 1.952,?

Accepted Answer

Series pattern Previous number/5 ∴ Missing term = 244/5 = 48.8

Question 19

12, 15, 36,?, 480, 2415, 14508

Accepted Answer

Series pattern 12 x 1 + 3 x 1 = 15 15 x 2 + 3 x 2 = 36 36 x 3 + 3 x 3 = 117 Should come in place of ? 117 x 4 + 3 x 4 = 480 480 x 5 + 3 x 5 = 2415 2415 x 6 + 3 x 6 =14508

Question 20

Find the fifteenth term of the arithmetic progression 3, 9, 15, 21, ....?

Accepted Answer

In the given AP, we have a = 3, d = (9 - 3) = 6, n =15 T15 = a + (n - 1)d = 3 + (15 -1)6 = 3 + 84 = 87

Odd Man Out and Series Questions