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Maths Puzzle
Find out the wrong term in the series given below:-
11, 5, 20, 12, 40, 26, 74, 54
Read Solution (Total 4)
-
- consider alternate numbers.
5 12 26 54, differences are doubling 7 14 28.
for 11 20 40 74 differences are 9 20 34
if number 40 is made 38
11 20 38 74, differences are 9 18 36
so wrong term is 40. - 13 years agoHelpfull: Yes(4) No(2)
- 38 is wrong term.
11, 5, 20, 12, 40, 26, 74, 54
two series are
11,20,40,74 ...
and
5,12,26,54
In case of 11,20,40,74 ...
20 = 11*2-2
next number should be 20*2-2=38
as 74= 38*2-2
so wrong term is 40 which should be 38. - 12 years agoHelpfull: Yes(3) No(1)
- Take the pair of terms
11+5=16
20+12=32
40+26=66
74+24=128
Except the pair(40,26) all other are divisible by 16
12-5=7
26-12=14
54-26=28
from the above we know that 26 is placed correct
so the answer is 40 - 12 years agoHelpfull: Yes(1) No(1)
- Take the alternate terms:
11, 20, 40, 74
and 5, 12, 26, 54
The difference between the first sequence of nos. are
11 (9) 20 (20) 40 (34) 74 ---------- A
and 5 (7) 12 (14) 26 (28) 54 ----------- B
From ' B ' we can see that the difference between the nos.(i.e. within brackets) are increasing by double...
Similarly, for ' A ' also to exhibit the similar property, 40 should be corrected to "38"...
Hence sequence ' A ' will become,
11 (9) 20 (18) 38 (36) 74
Now we can see that the difference between the nos. make sense!!!!
40 is the faulty no. Make it 38... - 12 years agoHelpfull: Yes(0) No(0)
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