The compound interest on Rs.2800 for 18 months at 10% p.a is = ?

1Rs. 420
2Rs. 434
3Rs. 436.75
4Rs. 441.35

Answer:- 1

Explanation:-

Solution:

\begin{aligned} Given, Principal, P = R s . 2800 \\ Compoind rate, R = 10 % per annum \\ = \frac{10}{2} = 5 % half - yearly \\ Amount \\ = Rs . [2800 \times (1 + \frac{10}{100}) (1 + \frac{5}{100})] \\ = Rs. (2800 \times \frac{11}{10} \times \frac{21}{20}) \\ = Rs. 3234 \\ ∴ C .I .  =  Rs. (3234 - 2800) \\ = Rs. 434 \end{aligned}

$\eqalign{ & {\text{Given,}}\,{\text{Principal}},\,P = Rs.\,2800 \cr & {\text{Compoind}}\,{\text{rate}},\,R = 10\% \,{\text{per}}\,{\text{annum}} \cr & = \frac{{10}}{2} = 5\% \,{\text{half - yearly}} \cr & {\text{Amount}} \cr & = {\text{Rs}}{\text{.}}\left[ {2800 \times \left( {1 + \frac{{10}}{{100}}} \right)\left( {1 + \frac{{5}}{{100}}} \right)} \right] \cr & = {\text{Rs.}}\left( {2800 \times \frac{{11}}{{10}} \times \frac{{21}}{{20}}} \right) \cr & = {\text{Rs. }}3234 \cr & \therefore {\text{C}}{\text{.I}}{\text{. = Rs.}}\left( {3234 - 2800} \right) \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {\text{Rs. }}434 \cr}$