Latest 3i-Infotech Aptitude Question SOLUTION: Find the smallest number in a GP whose sum is 38 and product 1728 (a) 12 (b) 20 (c) 8 (d) none of these

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Find the smallest number in a GP whose sum is 38 and product 1728

(a) 12 (b) 20 (c) 8 (d) none of these

Asked In 3i-Infotech sawan kumar (12 years ago)

Solved Dr.Dipin Singh Read Solution (3)

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Read Solution (3) :

Himanshu Mittal  (12 years ago)

In GP :- a/r+a+ar....=38
a(1+r+r^2)=38r......eq1
Product a^3=1728
a=12
now put this value in eq1
12(1+r+r^2)=38r
r=2/3 and 3/2..so sallest number is 8,12,20

Is this solution Helpfull? Yes (31) | No (11)  

Dr.Dipin Singh  (12 years ago)

Gp is 8,12,18.
So smallest no. Is 8.

Is this solution Helpfull? Yes (13) | No (11)  

pavantony  (4 years ago)

let, GP: a/r+a+a+ar..=38
take a/r as common
a/r(1++r^2+...)=38
a(1++r^2+...)=38r
We know that product in GP= a^3
a^3=1728
a=12
sub in the above equation
12(1+r+r^2...)=38r
solving r=3/2 and 2/3
now 12/r=12/(3/2)=8
Hence... Option C)8

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