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.

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? : (.

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)

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.

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)

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.

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

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

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)

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)

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)

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

So next number is 24.


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