Latest Elitmus Aptitude Question SOLUTION: f(x+y)=f(x)*f(y) f(1)=1.6, If f(1)+f(2)+f(3)+....+f(n) lies between 24 and 27. Find the value of n?

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(#M40023873) ELITMUS question Functions Keep an EYE

f(x+y)=f(x)*f(y)
f(1)=1.6,
If f(1)+f(2)+f(3)+....+f(n) lies between 24 and 27. Find the value of n?

Asked In Elitmus KESHAV KUNAL (11 years ago)

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Priyansh   (11 years ago)

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 ....

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rohit tandon  (11 years ago)

n=5...
1.6(1+2+3+4+5)=24
&
1.6(1+2+3+4+5+6)=33.6

since f(1)=1.6;f(2)=3.2; f(3)=4.8; f(4)=6.4

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Ramesh.V  (11 years ago)

f(1)=1.6
f(2)=f(1)+f(1)=1.6+1.6=3.2
f(3)=4.8
f(4)=6.4
f(5)=8.0
f(24)=38.4
f(27)=43.2.

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