Question

In what time will a sum of money double itself at 15% per annum?​

Answer 1

Answer:

Let the si be 100

sum=200

ACQ,

$\frac{100 \times \: si}{r \times p} \\ \\ \frac{100 \times 100}{200 \times 15} = 3years \: 3months \: approx$

Answer 2

$\displaystyle\huge\red{\underline{\underline{Solution}}}$

FORMULA TO BE IMPLEMENTED

Principal = p

Rate of interest = r %

Time = t years

Then

$\displaystyle \: Interest = I = \frac{prt}{100}$

TO DETERMINE

In what time a sum of money double itself at 15% per annum

CALCULATION

Let

Principal = p

Rate of interest = r %

Time = t years

Amount after t years = 2p

Interest = 2p - p = p

So

$\displaystyle \: p = \frac{p \times 15 \times t}{100}$

$\implies \: \displaystyle \: t = \frac{100}{15}$

$\implies \: \displaystyle \: t = \frac{20}{3}$

$\implies \: \displaystyle \: t = 6 \frac{2}{3}$

RESULT

SO THE REQUIRED TIME IS

$\displaystyle \: 6 \frac{2}{3} \: \: years = 6 \: years \: 8 \: months$