A sum of Rs 48,000 was lent out at simple interest and at the end of

1.	A sum of Rs 48,000 was lent out at simple interest and at the end of 2 years and 3 months the total amount was Rs 55,560. Find the rate of interest per year.
Answer» Given Principal P = Rs 48,000 Time n = 2 years 3 months = 2 + \(\frac{3}{12}\) years = 2 + \(\frac{1}{4}\) years = (\(\frac{8}{4}\) + \(\frac{1}{4}\)) years = \(\frac{9}{4}\) years Amount A = Rs 55,660 A = p + 1 55660 = 48000 + I I = 55660 – 48000 = Rs 7660 ∴ Interest for \(\frac{9}{4}\) years = Rs 7660 Simple interest = \(\frac{pnr}{100}\) 7660 = 48000 x \(\frac{9}{4}\) x \(\frac{r}{100}\) r = \(\frac{7660\times4\times100}{9\times48000}\) = 7.09 % = 7 % Rate of interest = 7 % Per annum.

A sum of Rs 48,000 was lent out at simple interest and at the end of 2 years and 3 months the total amount was Rs 55,560. Find the rate of interest per year.

Answer»

Given Principal P = Rs 48,000

Time n = 2 years 3 months

= 2 + \(\frac{3}{12}\) years

= 2 + \(\frac{1}{4}\) years

= (\(\frac{8}{4}\) + \(\frac{1}{4}\)) years

= \(\frac{9}{4}\) years

Amount A = Rs 55,660

A = p + 1

55660 = 48000 + I

I = 55660 – 48000

= Rs 7660

∴ Interest for \(\frac{9}{4}\) years = Rs 7660

Simple interest = \(\frac{pnr}{100}\)

7660 = 48000 x \(\frac{9}{4}\) x \(\frac{r}{100}\)

r = \(\frac{7660\times4\times100}{9\times48000}\)

= 7.09 %

= 7 %

Rate of interest = 7 % Per annum.