Logical Reasoning - Number Series - Discussion

8,11,[21],15,18,[21],22,25,[21],29,32,[21]

1st no is 8,when 7 is added ,it gives 15 (4th number in series)
2nd no is 11 ,again when 7 is added,it gives 18(5th no in series)
21 is interpolated as every 3rd no.


4th no is 15 ,when 7 is added,it gives 22 (7th no)
5th no is 18,when 7 is added,it gives 25 (8th no)
again 21 is interpolated as 3rd no (here its 6th).


7th no is 22 ,when 7 is added,it gives 29 (10th no)
8th no is 25,when 7 is added,it gives 32 (11th no)
again 21 is interpolated as 3rd no (here its 9th).and so on.....

8 11 [21] 15 18 [21] 22 25 [21] 29 32 [21] 36 39 [21] 43 46 [21] ....

Here 3, 4 is added alternatively and [21] injected as given below:

Inital = 8
8 + 3 = 11
********** [21]
11 + 4 = 15
15 + 3 = 18
********** [21]
18 + 4 = 22
22 + 3 = 25 <----- Required Answer
********** [21] <----- Required Answer
25 + 4 = 29
29 + 3 = 32
.........etc

SOLUTION:
Here number 21 put as a interpolatn dat means only to confuse you. So just excluding that series will be like as:
8+3=11 (add 3 & interpolation 21)
15+3=18 (add 3 & interpolation 21)
Now 22+3 =25 (add 3 & interpolation 21)

So answer wil be B) 25 21 because 25 final anwer and 21 as a interpolation.

Hope now you get it.

What is your confusion boss it is easy to get because hare to first number first 3 is added and then as third number interpolation would come and then what is there before interpolation number that would be added by 4 like this it will be go on.

8+3 = 11
11+4 = 15
15+3 = 18
18+4 = 22
From above we can conclude as difference b/w first two no.is 3.
Third no. is interpolation, it is repeated as every third no.
so next pair is 25 21 (22+3 =25)

8+3 = 11
11+4 = 15
15+3 = 18
18+4 = 22
From above we can conclude as difference b/w first two no.is 3.
Third no. is interpolation, it is repeated as every third no.
so next pair is 25 21 (22+3 =25)

(8+3)=11 & 21 is common in this series.
(15+3)=18 & 21 is common in this series.
(22+3)=25 & 21 is common in this series.

So, 8, 11, (21), 15, 18, (21), 22, 25, (21),...

There are two condition is here

1. Every 3rd number is 21
2. Difference between 2 and 1 number is 3.

In this way,
8-11=3
21
15-18=3
21
22-25=3. so the answer is 25 21

21 is common. Choose the difference b/w alternate numbers.
8 11 diff is 7
15 18
22
8-15 = 7
11-18 =7
So, 18 = 7 = 25 :22 25 is the answer.

Leaving 21 as a third number.

8 + 3 = 11,
15 + 3 = 18,
22 + 3 = 25 so answer will be 25 21, and also first number difference is 7.