Latest m4maths Aptitude Question SOLUTION: 7, 15, 25, 39, 61, ? Options 1) 77 2) 79 3) 81 4) 83 5) 87 6) 91 7) 93 8) 99 9) 107 10) none of these

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(#M40010534) M4MATHS question next number Keep an EYE

7, 15, 25, 39, 61, ?

Options 1) 77
2) 79
3) 81
4) 83
5) 87
6) 91
7) 93
8) 99
9) 107
10) none of these

Asked In m4maths Mukesh (11 years ago)

Unsolved Read Solution (9)

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SDeep Bhattacharya  (11 years ago)

Let the next number be ‘T’
Now let’s take the differences of the consecutive terms of the given sequence:
15 – 7 = 8;
25 – 15 =10;
39 – 25 =14;
61 – 39 = 22;
T – 61 = D; (Let)
Now if we observe the sequence of the differences : 8 , 10 , 14 , 22 ,D,….
We can clearly observe that the differences of consecutive terms are : 2 ,4,8,(D – 22 )….
Where 2=2^1;
4=2^2;
8=2^3;
Therefore 4th term will obviously be [(2^4)=16]; So, (D – 22)=16; => D=38;
Therefore, T= 61+D =61+38=99;
So,The next number will be 99.
The correct answer is OPTION 8.) 99

Is this solution Helpfull? Yes (22) | No (1)  

PARAG KAMRA  (11 years ago)

99(ans)
first series contain sum of 7
7,25,61
2+5=7
6+1=7
2nd series contain difference of 6
15,39,?
1+5=6
3+9=12
so choose the option for that sum of digit contain 18
so 99 contain 9+9=18
so 99 is ans

Is this solution Helpfull? Yes (9) | No (13)  

Laltu Karmakar  (11 years ago)

7 15 25 39 61
Difference betwn 8 10 14 22
again difference 2 4 8
now 16
22+16=38
so 61+38=99

Is this solution Helpfull? Yes (4) | No   

Lorna A. Canillo  (11 years ago)

1st term is 7, 2nd term 7+8=15, 3rd term 15+10=25, 4th term 25+14=39,
5th term 39+22=61, 6th term 61+38=99, 7th term 99+70=169
therefore, the answer to this puzzle is 99.

Is this solution Helpfull? Yes (3) | No (1)  

nagesh  (11 years ago)

7, (7+8), (15+8+2^1), (25+8+2^1+2^2), (39+8+2^1+2^2+2^3),(61+8+2^1+2^2+2^3+2^4) so ans is 99

Is this solution Helpfull? Yes (2) | No (7)  

vivek tiwari  (11 years ago)

first series 7,25,61
second series 15,39,x
difference in first series gets multiplied by 2
25-7=18,61-25=36;
so
39-15=24
x-39=48
x=87

Is this solution Helpfull? Yes (1) | No (12)  

nivetha91  (11 years ago)

answer:99 the difference is 7-15=8 15-25=10 25-39=14 39-61=22 then next difference is 38.so 61+38=99

Is this solution Helpfull? Yes (1) | No   

Madhu  (11 years ago)

answer is 99
7,1+5=6,2+5=7,3+9=12,6+1=7,9+9=18
7,6,7,12,7,18
so alternative odd position are having 7
alternative even position are having multiples of 6 so 9+9=18
answer is 99

Is this solution Helpfull? Yes | No (7)  

SHUBHAM KARODIYA  (11 years ago)

Ans 8) 99
because every next number= 2*previous number-constant number
this constant number is started with -1 and for every next time 6 is added every time
hence
7*2-(-1)=15
15*2-(5)=25
25*2-(11)=39
39*2-(17)=61
61*2-(23)=99
hence sequence is 7,15,25,39,61,99

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