Question

If compound interest on a certain sum of money at 5% per annum for 2 years is Rs. 246.

The simple interest on the same sum for 4 years at 8% per annum is :-


(a) Rs. 786
(b) Rs. 768
(c) Rs. 815
(d) Rs. 840​

Answer 1

Answer:

Option b

C.I=P (1+r/100)^2-1

246=p (1+5/100)^2-1

246=p (1+1/20)^2-1

246=p (21/20)^2-1

246=p (441/400-400/400)

246=p×41/400

p=246×400/41

p=2400

S.I=p×r×t/100

s.i=2400×8×4/100

s.i=24×8×4

s.i=768

option b

Answer 2

Answer :-

(b) Rs. 768

Explanation :-

$\sf \color{red} C.I. = P \: \bigg[ \bigg(1 \: + \: \frac{ x }{100} \bigg) ^{n} \: - 1 \bigg]$

$\sf \color{lime}246 = P \: \bigg [ \bigg(1 \: + \: \frac{5}{100} \bigg)^{2} \: - 1 \bigg]$

$\sf \color{purple} 246 = P \: \bigg [ \bigg( \frac{105}{100} \bigg)^{2} \: - 1 \bigg]$

$\sf \color{cyan} 246 = P \: \bigg [\bigg( \frac{21}{20} \bigg)^{2} \: - 1 \bigg]$

$\sf \blue {P = 2400}$

$\mathfrak \color{orange} So, \: SI \: on \: Rs. \: 2400 \: for \: 4 \: years \: at \: 8 \: percent \: S.I.$

$\sf \color{pink} \implies S.I. = \frac{2400 \: \times \: 4 \: \times \: 8}{100}$

$\sf \color{green} = 24 \: \times \: 32 \: = 768$

$\mathfrak \color{red}{Hence, \: option \: B \: is \: correct.}$