Latest CTS Aptitude Question SOLUTION: 108 56 29 15 8 x Find x?

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(#M40033050) CTS Numerical Ability question Series Keep an EYE

108 56 29 15 8 x
Find x?

Asked In CTS Dhananjay Mehrotra (10 years ago)

Unsolved Read Solution (14)

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Read Solution (14) :

srikanth  (10 years ago)

tetranacci numbers are a generalization of the Fibonacci numbers defined by T_0=0, T_1=1, T_2=1, T_3=2, and the recurrence relation

Answer is 4 :
T_n=T_(n-1)+T_(n-2)+T_(n-3)+T_(n-4)

for n>=4. They represent the n=4 case of the Fibonacci n-step numbers. The first few terms for n=0, 1, ... are 0, 1, 1, 2, 4, 8, 15, 29, 56, 108, 208, ...

Is this solution Helpfull? Yes (28) | No (11)  

kumar satyanand  (10 years ago)

108-56=52 now 52=27*2-2
56-29=27 now 27=14*2-1
29-15=14 now 14=7*2-0
15-8=7 now 7=(8-x)*2-(-1)
8-x=(8-x) so, 7=16-2x+1
2x=17-7=10
x=5 ans.

Is this solution Helpfull? Yes (16) | No (1)  

Subrata Patra  (10 years ago)

x is 4
first one is 108
2nd is (108+4)/2=56
3rd is (56+2)/2=29
4th is (29+1)/2=15
5th is (15+1)/2=8
6th will be (8+0)/2=4

Is this solution Helpfull? Yes (9) | No (11)  

prasanth  (10 years ago)

It is a generalization of the fibonacci sequence knows as the tetranacci sequence. It is similar to the fibonacci sequence where each subsequent number is the sum of the previous two. With a tetranacci sequence each subsequent number is the sum of the previous four, so the full sequence looks like this: 0, 0, 0, 1, 1, 2, 4, 8, 15, 29, 56, 108, 208, 401. This sequence can be very hard if you have no idea were to look, therefore learn to recognise these types of sequences.

Is this solution Helpfull? Yes (2) | No (1)  

niranjan  (8 years ago)

tetranacci numbers are a generalization of the Fibonacci numbers defined by T_0=0, T_1=1, T_2=1, T_3=2, and the recurrence relation

Answer is 4 :
T_n=T_(n-1)+T_(n-2)+T_(n-3)+T_(n-4)

for n>=4. They represent the n=4 case of the Fibonacci n-step numbers. The first few terms for n=0, 1, ... are 0, 1, 1, 2, 4, 8, 15, 29, 56, 108, 208, ...

Is this solution Helpfull? Yes (2) | No   

ganesh ramesh gawali  (10 years ago)

(108/2)+2=56
(56/2)+1=29
(29/2)i.e 14+1=15
(15/2)i.e 7+1=8
(8/2)+2=6
Ans:-6

Is this solution Helpfull? Yes (1) | No (10)  

kumar satyanand  (10 years ago)

108-56=52 now 52=27*2-2
56-29=27 now 27=14*2-1
29-15=14 now 14=7*2-0
15-8=7 now 7=(8-x)*2-(-1)
8-x=(8-x) so, 7=16-2x+1
2x=17-7=10
x=2 ans.

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

Meenu   (10 years ago)

ans is 4
4
4*2-0=8 (first we subtract 0)
8*2-1=15 ( next we subtract 1)
15*2-1=29 (now we subract sum of 0+1=1 ie sum of previous values we subtracted)
15*2-1=29 (now we subtract 0+1=1 from the product term)
29*2-2=56 (now we subtract 0+1+1=2 i.e sum of all previous nos we subtracted)
56*2-4=108 ( here again we subtract sum of all previous nos we subtracted ( i.e 0+1+1+2=4) from the product term)
that means the first no should be 4,so answer is 4

Is this solution Helpfull? Yes (1) | No (4)  

rakesh  (10 years ago)

This might be right answer , just check before you conclude :

8*2 = 16 - 1 = 15
15*2 = 30 - 1 = 29
29*2 = 58 - 2 = 56
56*2 =112 - 4 = 108

here the logic is for odd numbers [ -1 ],for even numbers[ - starts with 2 if any even numbers follows then - (multiples of 2) ]

hence answer is 5 * 2 = 10 - 2 = 8 .

Is this solution Helpfull? Yes (1) | No (2)  

Mani kandan  (10 years ago)

can any 1 tell the correct answer

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

muni  (8 years ago)

it is following Fibonacci series..... 0,1,1,2,4,8,16........
56+56=112-4=108
29+29=58-2=56
15+15=30-1=29
8+8=16-1=15
4+4=8-0=8
so the ans is.........4

Is this solution Helpfull? Yes (1) | No   

ADEEB AHMAD   (10 years ago)

plzz check the ques. i think the 2nd no. should be 66.
then the ans will be 1.

Is this solution Helpfull? Yes | No (6)  

rohan chawla  (10 years ago)

answer is 5
5,8,15,29,56,108

Is this solution Helpfull? Yes | No (2)  

preethi v v   (10 years ago)

ans is 5
108/2=54 ,54+2
56/2=28,28+1
29/2=14, 14+1
8/2=4,4+1=5

Is this solution Helpfull? Yes | No (2)  

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