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11. In the following number series a wrong number is given. Find out the wrong number.
150, 450, 750, 1060,1350,1650,1950

Discuss
Solution:

By adding 300 to each term, we get the next term. 1060 is wrong term. It should be 1050.

12. What will come at the place of question mark ?
5690, 5121, 4552, 3983, 3414, 2845, ?

Discuss
Solution:

By subtracting 569, we get the next term.
Required number,
= 2845-569
= 2276.

13. What will come at the place of question mark ?
6, 13, 28, 59, ?, 249.

Discuss
Solution:

First term → 6
Second term → (6*2+1) = 13
Third term → (13*2+2) = 28
Fourth term → (28*2+3) = 59
Fifth term → (59*2+4) = 122
Sixth term → (122*2+5) = 249
So, the required term = 122.

14. What will come at the place of question mark ?
4, 8, 10, 14, 16, 20, ?

Discuss
Solution:

Above series contains two sub-series in it.

4, 10, 16, 22

8, 14, 20

Each of both term there is difference of 6 i.e. next term is 6 greater than previous term.

15. What will come at the place of question mark ?
9, 17, 33, 65, ?

Discuss
Solution:

First term → 9

Second term → (9 *2 -1) = 17

Third term → (17 *2 -1) = 33

Fourth term → (33 *2 -1) = 65

Fifth term → (65 *2 -1) = 129
 

16. What will come at the place of question mark ?
2, 3, 6, 15, ?, 123

Discuss
Solution:

First term → 2

Second term → (2 *3 -3) = 3

Third term → (3 *3 -3) = 6

Fourth term → (6 *3 - 3) = 15

Fifth term → (15 *3 - 3) = 42

Sixth term → (42 *3 - 3) = 123 

17. In the following number series a wrong number is given. Find out the wrong number.

1, 3, 10, 21, 64, 129, 356, 777

Discuss
Solution:

The given pattern is,
2nd term → 1*2+1 = 3
3rd term → 3*3+1 = 10
4th term → 10*2+1 = 21
5th term → 21*3+1 = 64
6th term → 64*2+1 = 129
7th term → 129*3+1= 388
So, 7th term 356 is wrong and must be replaced by 388.

18. What will come at the place of question mark ?
9, 27, 31, 155, 161, 1127, ?

Discuss
Solution:

Given pattern is,
2nd term → 9*3 = 27
3rd term → 27+4 = 31
4th term → 31*5 = 155
5th term → 155+6 = 161.
6th term → 161*7 = 1127
Missing term → 1127+8 = 1135.

19. What will come at the place of question mark ?
2, 7, 27, 107, 427, ?

Discuss
Solution:

The pattern is,
2nd term → 2 +(5 *12) = 7
3rd term → 7 +(5 *22) = 27
4th term → 27 +(5 *42) = 107
5th term → 107 +(5 *82) = 427
Missing term → 427 +(5 *162) = 1707

20. Sunday, Monday, Wednesday, Saturday, Wednesday, Monday, .....

Discuss
Solution:

Sunday to Monday = no gap
Monday to Wednesday = One day gap.
Wednesday to Saturday = Two days gap.
Saturday to Wednesday = Three days gap.
Wednesday to Monday = Four days gap.
In the next term there must be five days and six days gap.
So, Next term would be Sunday, Sunday.