Question

In what time will a sum of rs 3750 at 20%per annum compounded annually amount to rs 6480
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Answer 1

${\bold{\underline{\underline{Answer:}}}}$

${\bold{\therefore Time=3\:years}}$

${\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\underline \bold{Given : } \\ \implies Principal(p) = 3750 \: rupees \\ \\ \implies Amount(a) = 6480 \: rupees \\ \\ \implies Rate(r) = 20\% \\ \\ \underline \bold{To \: Find: } \\ \implies Time(t) = ?$

• According to given question :

$\bold{Using \: formula \: of \: Compound \: Interest : } \\ \implies A = p(1 + \frac{r}{100} )^{t} \\ \\ \implies 6480 = 3750 \times (1 + \frac{\cancel{20}}{\cancel{100}} ) ^{t} \\ \\ \implies 6480 = 3750 \times (1 + 0.2)^{t} \\ \\ \implies \frac{\cancel{6480}}{\cancel{3750}} = (1.2)^{t} \\ \\ \implies 1.728 = (1.2) ^{t} \\ \\ \implies (1.2)^{3} =( {1.2})^{t} \\ \\ \bold{Both \: side \: bases \: are \: same } \\ \bold{So ,\: powers \: are \: also \: same : } \\ \\ \bold{\implies t = 3 \: years}$