Question

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

Answer 1

Answer:

lot the principal is equal to 100

time =x

intrest =ptr/100

100=100×15×x/100

100×100/100×15=x

x=1000/15

x=6.6

x=6 years and 6months

this in simpleintrest

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

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