Question

a sum amoints to rs.1326 in 6 years at 5% per annum . in what time time will this sum double itself at the same rate of interest

Answer 1

Answer =

20 years

Explaination :

Let's consider SI as x

$\therefore$ Principal = 1326 - x

$\large = > SI = \frac{(1326 - x )\times 5 \times 6}{100}$

$\large= > x = \frac{(1326 - x) \times 30}{100}$

$\large = > x \: = \frac{3(1326 - x)}{10}$

$\large = > 10x + 3x = 3978$

$\large= > 13x = 3978$

$\large= > x = \frac{3978}{13}$

$\large{\green{\boxed{\green{\boxed{\red{\textsf{x = 306}}}}}}}$

$= > P \: = \: Amount - Interest$

$\large= > 1326 - 306$

$\large{\green{\boxed{\green{\boxed{\red{\textsf{1020}}}}}}}$

According to the condition of the question,

$= > P \: = \: SI$
$\large{\green{\boxed{\green{\boxed{\red{\textsf{\therefore{SI = RS.1020}}}}}}}}}$

$\large = > T \: = \frac{SI \: \times \: 100}{P \times R}$

$\large= > \frac{1020 \times 100}{1020 \times 5}$

$\large= > \frac{100}{5}$

$\large= > \frac{20}{1}$

$\large{\green{\boxed{\green{\boxed{\red{\textsf{20 years}}}}}}}$

$\therefore$ Time is 20 years.

Answer 2

Answer:

Amount =Rs. 1326

Time = 6 years

Rate of Interest = 5%

According to the condition,

If the amount is doubled means

Amount = 1326 × 2 =Rs. 2652

Simple Interest = 2652 - 1326 = 1326