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.

Shubham gour said:   4 years 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.
(34)

Maryam said:   7 years ago
The sequence I was following.

(5*2)-4.
(6*2)-3.
(9*2)-2.
But
(15*2)-1 =29 (the pattern is same from above, the answer only changes in the last step).
(2)

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)

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)

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)

Naveen Kumar said:   8 years ago
I agree with your explanations @Venuu and @Jitender.
(1)

Biplab said:   8 years ago
5 9 ? =(15+25)
6 15 40

cross adding between 9+6=15 so 15 +25=40.
(1)

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

So next number is 24.

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.


Post your comments here:

Your comments will be displayed after verification.