Verbal Reasoning - Series Completion - Discussion

Discussion Forum : Series Completion - Section 1 (Q.No. 9)
Directions to Solve

Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.


9.
5, 6, 9, 15, ?, 40
21
25
27
33
Answer: Option
Explanation:

The pattern is + 1, + 3, + 6,....., i.e. + 1, + (1 + 2), + (1 + 2 + 3),.....

So, missing term = 15 + (1 + 2 + 3 + 4) = 25.

Discussion:
15 comments Page 1 of 2.

Mona said:   1 decade ago
But acording to + 1, + 3, + 6, . , next digit is +9.

So next number is 24.

Jitender said:   1 decade ago
Add the position of no. to it like:-
5+1=6
6+(1+2)=9
9+(1+2+3)=15
15+(1+2+3+4)=25

So the ans is 25
(1)

Alric said:   1 decade ago
I like the explanation that jitender gave that is more understandable.

Prashanthi said:   1 decade ago
Difference b/w 1,3 is 2.

3, 6 is 3 and next difference should be 4 so it becomes 6+4 = 10 and finally 15+10 = 25.

Sulekha said:   1 decade ago
According to the given answer the next number should be (25*1)+(1+2+3+4+5) = 35. But the next number is 40 in the given series.

Anyone can explain? : (.

Wesley said:   1 decade ago
5+1 = 6.
6+(1+2) = 9.
9+(1+2+3) = 15.
15+(1+2+3+4) = 25.
25+(1+2+3+4+5) = 40.
(1)

Abhishek said:   1 decade ago
Ignore first number (5), now 6+9=15, 15+25=40.

Ramya said:   9 years ago
Differences between first four numbers in series are 1, 3, 6.

1*1 + 2 = 3.

3*1 + 3 = 6.

So.

6*1 + 4 = 10.

The next number is 10 + 15 = 25.

Bhanu said:   8 years ago
Can anyone explain clearly?

Venuu said:   8 years ago
You should add there positions respectively.

5, 6, 9, 15_40.

1) 5+1=6.
2) 6+2+1=9.
3) 9+3+2+1=15.
4) 15+4+3+2+1=25.
5) 25+5+4+3+2+1=40.
(1)


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