Question

if the sum of money become 13/4 times in 2 years under an annual compounded annually, find the rate of compound interest. ​

Answer 1

Answer:

Step-by-step explanation:

Let sum=x

Time=2years

Let rate=r%p.a

Amount=13/4x

now,

A=P+CI

CI=P(1+r/100)^n

=x(1+r/100)^2

So,

A= x(1+r/100)^2+x

13/4x=x(1+r/100)^2+x

=x(1^2+r^2/100^2+2×r/100×1)+x=13/4x

=x(r^2/10000+1+r/50)=13/4x-x

=(r^2+10000+200r)/10000=9/4x×1/x

r^2+10000+200r=9/4×10000

r^2+200r+10000=2500×9

r^2+200r=22500-10000

r^2+200r=12500

r^2+200r-12500=0

r^2+250r-50r-12500=0

r(r+250)-50(r+250)=0

(r+250)(r-50)=0

r+250=0

r=-250

r-50=0

r=50%p.a

as r%couldn't be negative r%=50%