Question

at what rate per cent will a sum of rs 640 be compounded to rs 774.40 in 2 years​

Answer 1

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Principle=640

Amount=774.40

Time=2yrs

Rate=?

Amount=p(1+r/100)^n

=774.40=640(1+r/100)^2

774.40÷640=(1+r/100)^2

(11/10)^2=(1+r/100)^2

(Both powers are cut)

11/10=1+r/100

11/10-1/1=r/100

1/10=r/100

R=100/10

R=10%. Answer

Therefore rate %=10%.