Progression Practice Test 1

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Question : 10 of 23

Marks: +1, -0

Find three numbers of GP whose sum is 52 and product is 1,728.

5, 12, 25
3, 13, 36
4, 13, 36
4, 12, 36
None of the above

Solution:

Let the three numbers be

a/ r , a,

and

a r

.
Given that

a/r .a.ar=1728

⇒a=12

a/r+a+ar=52

⇒12/r+12+12r=52

⇒3r^2-10r+3=0

⇒(3r-1)(r-3)=0

⇒r=1/3,3

Hence, the numbers are 4, 12, 36 (or) 36, 12, 4.

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