GATE2014 EC-2: GA-5

Question

Fill in the missing number in the series.

$2$     $3$      $6$      $15$  ___  $157.5$       $630$

Comments

2 3 6 15 _________________ 157.5  630

this question is time consuming to find out the series in one go

but with practice we can succeed. Actually this question has two multiple series going on .

firstly of 0.5 multiplication but those 1.5 are incrementing by 1 and then multiplying.

Secondly , we are multiplying by natural number 1 ,2 ,3 ………

So our answer comes as

 

2 * 1.5 = 3

3 * 2  = 6

6 * 2.5 = 15

15 * 3 = 45

45 * 3.5 = 157.5

157.5 * 4 = 630

So , the answer is 45.

Answer 1

$2\times 1.5=3$

$3\times 2=6$

$6\times 2.5=15$

$15\times 3=45$ is answer

$45\times 3.5=157.5$   means each time increase multplication factor by $0.5$

Comments

How you get this? Any trick for it. I have been trying since half hour.