Question

find the time in which the principal of rs 5000 will earn simple interest of rs 1800 at the rate of 6% per annum​

Answer 1

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$\underline{ \underline {\bold{ \: GIVEN \: \: : }}} \to \\ \\ \bold{Principal \: ,\: P = Rs. \: 5000} \\ \\ \bold{Simple \: \: interest \:, \: SI = Rs. \: 1800} \\ \\ \bold{Rate \: \: of \: \: interest \: ,\: R = \: 8\%} \\ \\ \\ \underline{ \underline{ \bold{ \: \: TO \: \: FIND \: \: : }}} \to \: \: \: \: \: \: \bold{Time \: \: ,\: T = ?}$

$\underline{ \bold{ \: \: We \: \: know \: \: that \: \: }} \\ \\ \\ \bold{SI = \frac{P \times R \times T}{100} } \\ \\ \bold{ \Longrightarrow \: P \times R \times T \: = \: SI \times 100} \\ \\ \bold{ \therefore} \: \: \boxed{ \bold{ \: T \: = \: \frac{ \: \: SI \times 100 \: \: }{ P\times R} \: }}$

$\underline{ \bold{ \: \: Using \: \: this \: \: formula \: \: }} \\ \\ \\ \bold{ \therefore \: \: T \: = \: \frac{ \: 1800 \times 100 \: }{5000 \times 6} } \\ \\ \bold{ \: \: \: \: \: \: \: \: \: \: = \frac{180000}{3000} } \\ \\ \bold{ \: \: \: \: \: \: \: \: \: \: = 6}$

$\bold{Hence} \\ \\ \bold{In \: \: \red{6 \: \: years \: \: } \: the \: \: principal \: \: of \: \: Rs. \: 5000} \\ \\ \bold{will \: \: earn \: \: simple \: \: interest \: \: of \: \: Rs. \: 1800} \\ \\ \bold{at \: \: the \: \: rate \: \: of \: \: 6\% \: \: per \: \: annum \: .}$

Answer 2

Given :-

Principal , P =Rs. 5000

Simple interest , SI = Rs. 1800

Rate of interest , R = 6%

We know that ,

S.I = P × R × T / 100

=>T = S.I × 100 / P × R



Using the above formula

T = 1800 × 100 / 5000 × 6

=> T = 180000 / 30000

=> T = 6

•°• Time = 6 years

So ,

In 6 years the principal of amount Rs. 5000 will earn simple interest of Rs. 1800 at the rate of 6% per annum .