Question

Find the principal which amounts to 245000 rupees if the compound
interest is 15000 rupees.​

Answer 1

Solution:-

We know that the amount A at the end of n years at the rate of R% per annum when the interest is compounded annually is given by

A \: = \: P \: \: (1 \: + \: \frac{R}{100} )^{n}

Here , Principal (P) = ₹ 15000, R = 10 % p.a and n = 3 years .

Therefore, amount (A) after 3 years

= ₹ 15000\: (1 \: + \: \frac{10}{100} )^{3}

= \: ₹ 15000\: ( \frac{11}{10} )^{3}

= \: ₹ 15000 \: \times \: \frac{11}{10} \: \times \frac{11}{10} \times \: \frac{11}{10} \: = \: ₹ \: 19965

Now, compound interest

= Amount (A) - Principal (P)

= ₹ 19965 - ₹ 15000 = ₹ 4965

Thus, the required compound interest is ₹ 4965