Question

The time by which a sum of money is 32 times of itself at the rate of C.I. If it doubles itself 20

in years:

(a) 320 years (b) 100 years

(c) 310 years (d) None of these
​

Answer 1

let sum=P

Time=2 Years

Amount=2P

According to the question

⇒P(1+

100

r

)

5

=2P

⇒(1+

100

r

)

5

=2

Cubic both side we gets

⇒(1+

100

r

)

15

=8

⇒P(1+

100

r

)

15

=8P

Hence,in 15 Years amount to eight times itself.