Latest Elitmus Aptitude Question SOLUTION: f(x+y)= f(x)*f(y); f(x)=1.6, f(1)+f(2)+f(3)+.........f(n) lies between 24 and 32 then what is the value of n.

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(#M40143531) ELITMUS Numerical Ability question asked on 29th march Keep an EYE

f(x+y)= f(x)*f(y); f(x)=1.6, f(1)+f(2)+f(3)+.........f(n) lies between 24 and 32 then what is the value of n.

Asked In Elitmus prem kishor (9 years ago)

Unsolved Read Solution (3)

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Read Solution (3) :

jeet  (9 years ago)

Firstly its f(1)=1.6
here it is given that f(x+y)=f(x)*f(y)
f(1)=1.6
f(2)=f(1)*f(1)=1.6*1.6
f(3)=f(2)*f(1)=1.6*1.6*1.6
similarly for f(4) = 1.6 ^ 4
thus forming the gp
sum of gp to n terms is (a(r^n-1))/(r-1)
here a=1.6 and r=1.6
(1.6((1.6)^n - 1))/(1.6 - 1) => 2.67((1.6)^n - 1) = for n=5 the value comng is 25.32 ,, thus the value of n=5

Is this solution Helpfull? Yes (20) | No (3)  

AWDHESH CHAUHAN  (9 years ago)

f(x)=1.6
f(x-1+1)=1.6 =>f(x-1+1)=f(x-1)*f(1)=1.6
now let f(x-1)=.8 and f(1)=2
so
f(1)=2
so f(2)=f(2-1+1)=f(2-1)*f(1)=f(1)*f(1)
so
f(2)=f(1)*f(1)=2*2=4
so f(3)=f(2)*f(1)=4*2=8
f(4)=f(3)*f(1)=8*2=16
now 2+4+8+16=30 lies in24 t0 32
so n=4

Is this solution Helpfull? Yes (5) | No (1)  

ANIL KUMAR  (9 years ago)

Given: - f(x+y)=f(x)*f(y) ___________(1) and 24

Is this solution Helpfull? Yes (2) | No   

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