What is the missing number of the following sequence 5, 39, 8, 9, 40, 11, 13, 27, 14, 15, ......,

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03 Oct 2016 Sequence

What is the missing number of the following sequence
5, 39, 8, 9, 40, 11, 13, 27, 14, 15, ......, 17

OPtion

1) 16
2) 28
3) 68
4) 42
5) 64
6) 36
7) 49
8) 52
9) 38
10)72

Solution

5, 39, 8, 9, 40, 11, 13, 27, 14, 15, ......, 17
(5, 39, 8), (9, 40, 11), (13, 27, 14), (15, ......, 17)
a b c
b = c^2 - a^2
8^2-5^2 = 64-25 = 39
11^2-9^2 = 121-81 = 40
14^2-13^2 = 196-169 = 27
Similarly
17^2-15^2 = 289-225 = 64

Correct Option: 5 Best Solution (15)

prakash sharma   8 years AGO

we divided this series into 3-3 pairs like
(5,39,8),(9,40,11),(13,27,14),(15,_,17)
we assume this series as (A,B,C)
then
B=(C-A)*(A+C)
eg-(5,39,8)
means 39=(8-5)*(5+8)
so same as in last pair of this series
B=(17-15)*(15+17)
B=64(Option 5 in answer)

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chetan   8 years AGO

(8+5)*(8-5) =39
(11+9)*(11-9) =40
(14+13)*(14-13) =27
(17+15)*(17-15) =64
so option 5 is correct

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G.S.Kantharao   8 years AGO

Series is5,39,8,940,11,13,27,14,15,...,17
(5,39,8),(9,40,11),(13,27,14),(15,......,17)
[5,{(8+5)(8-5)},8],[9,{(11+9)(11-9)},11],[13,{(14+13)(14-13)},14],[15,{(17+15)(17-15)},17]
Hence the number missing is 64 and right option is 5.

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Lakshmi Narayanan.k   8 years AGO

(5,39,8), (9,40,11), (13,27,14), (15,-,17).
5+8=13*3=39.
11+9=20*2=40.
13+14=27*1=27.
15+17=32*2=64(OPT 5)

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rrr.j   8 years AGO

5+8=13 so 13*3=39; (since difference of 8-5=3 we multiply with 13)
9+11=20 so 20*2=40; (same 11-9=2 so multiply with 20)
13+14=27 so 27*1;
15+17=32 so 32*2=64;
option 5)64

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Mukund Manohar   8 years AGO

(5,39,8),(9,40,11),(13,27,14),(15,_,17)
8+5=13 & 8-5=3
13*3=39
So,(5,39,8)
Applying the same logic,
11+9=20 & 11-9=2
20*2=40
So, (9,40,11)
14+13=27 & 14-13=1
27*1=27
So, (13,27,14)
17+15=32 & 17-15=2
32*2=64
So,(15,64,17)
64 is the missing number in the given sequence.

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manik garg   8 years AGO

taking 3 number at a time we get
(5+8)*(8-5)=39
similarly for all and at last
(17+15)*(17-15)=64

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Dinesh Sharma   8 years AGO

In general, take 3 consecutive number, says n1,n2,n3 and apply, (n3+n1)*(n3-n1)=n2

(8+5)*(8-5)=39
(11+9)*(11-9)=40
(14+13)*(14-13)=27
(17+15)*(17-15)=64

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Siva   8 years AGO

(5+8)*(8-5)=39,
(9+11)*(11-9)=40,
(13+14)*(14-13)=27,
(15+17)*(17-15)=64.

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gnanesh mannam   8 years AGO

8+5=13,8-5=3,,13×3=39,,
11+9=20,11-9=2,20×2=40
14+13=27,14-13=1,27×1=27,
17+15=32,17-15=2,32×2=64
answer is 64

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Lalit Kumar   8 years AGO

(5+8)*3=39
(11+9)*2=40
(13+14)=27
(15+17)*2=64

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nagarjuna   8 years AGO

5,39,8 :- 8+5=13 ,8-5=3 :- 13*3=39
9,40,11 :- 9+11=20 ,11-9=2 :- 20*2=40
......
15+17=32, 17-15=2 :- 32*2=64

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imran khan   8 years AGO

5+8=13*3=39
9+11=20*2=40
13+14=27*1=27
similarly 15+17=32*2=64

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SATHEESH V   8 years AGO

(5+8)*(8-5)=39
(9+11)*(11-9)=40
(13+14)*(14-13)=27
similarly
(15+17)*(17-15)=64

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KARTIK CHOUDHARY   8 years AGO

here we take the 3 numbers series and
5+8=13 and (8-5)*13=39
similarly(17+15)=32 and (17-15)*32=64

Like? Yes | No (1)