Question

find CI when p=12800 time= 3 Rate=10 ​

Answer 1

Solution :

$\underline{\bf{Given\::}}}}$

• Principal, (P) = Rs.12800
• Rate, (R) = 10% per annum.
• Time, (n) = 3 years

$\underline{\bf{To\:find\::}}}}$

Compound Interest.

$\underline{\bf{Explanation\::}}}}$

$\bigstar$Using formula of the compound annually :

$\boxed{\bf{Amount=Principal\bigg(1+\frac{R}{100} \bigg)^{n} }}}$

$\longrightarrow\sf{A=12800\bigg(1+\cancel{\dfrac{10}{100}} \bigg)^{3} }\\\\\\\longrightarrow\sf{A=12800\bigg(1+\dfrac{1}{10} \bigg)^{3} }\\\\\\\longrightarrow\sf{A=12800\bigg(\dfrac{10+1}{10} \bigg)^{3} }\\\\\\\longrightarrow\sf{A=12800\bigg(\dfrac{11}{10} \bigg)^{3} }\\\\\\\longrightarrow\sf{A=128\cancel{00}\times \dfrac{11}{\cancel{10}} \times \dfrac{11}{\cancel{10}}\times \dfrac{11}{10}}\\\\\\\longrightarrow\sf{A=\dfrac{128\times 11\times 11\times 11}{10} }$

$\longrightarrow\sf{A=\cancel{\dfrac{170368}{10} }}\\\\\longrightarrow\bf{A=Rs.17036.8}$

Now;

We know that compound Interest :

$\longrightarrow\sf{C.I.=Amount-Principal}\\\\\longrightarrow\sf{C.I.=Rs.17036.8-Rs.12800}\\\\\longrightarrow\bf{C.I.=Rs.4236.8}$

Answer 2

Given :-

• principle = Rs. 12800
• rate = 10%
• time = 3 years

To Find :-

• compound interest = ???

Formulae used :-

Amount = $\sf P ( 1 + \dfrac{rate}{100})^{time}$

CI = amount - principle

Explanation :-

➦ Amount = $\sf P ( 1 + \dfrac{rate}{100})^time$

➦Amount = $\sf 12800 ( 1 + \dfrac{10}{100})^3$

➦Amount = $\sf 12800 ( 1 + \dfrac{1}{10})^3$

➦Amount = $\sf 12800 ( \dfrac{11}{10})^3$

➦Amount = $\sf 12800( \dfrac{11\times 11 \times 11}{10\times 10 \times 10})$

➦Amount = $\sf 128 ( \dfrac{1331}{10})$

➦Amount = $\sf ( \dfrac{170368}{10})$

➦Amount = Rs. 17036.8

_____________

➦ CI = amount - principle

➦CI = Rs. ( 17036.8 - 12800)

➦CI = Rs. 4236.8

Answer :-

☆ CI = Rs. 4236.8