Question

Principal ($)	Rate of interest (%)	Time (years)	Simple interest ($)
750	a	2	60
1500	6	1	b

Using the data given in the table above, find the value of a and b.

• A. a = 8%, b = $90
• B. a = 4%, b = $45
• C. a = 8%, b = $45
• D. a = 4%, b = $90

Answer 1

The correct option is D a = 4%, b = $90

You know,
Simple interest $(S.I.)=\frac{P\times R\times T}{100}$
where,
$P$ = Principal amount
$R$ = Rate of interest in $\%$
$T$ = Time taken in years.

For first case:
Principal amount,$P=\$750$
$R=a\%$ and $T=2years$
Simple interest amount $S.I.=\$60$

Putting the values in the formula you have,
$S.I.=\frac{750\times R\times 2}{100}$
$\Rightarrow 60=15\times R$
$\Rightarrow R=4$

So, $a=4\%$

Similarly for second case:
Principal amount,$P=\$1500$
$R=6\%$ and $T=1year$
Simple interest amount $S.I.=\$b$

Putting the values in the formula we have,
$S.I.=\frac{1500\times 6\times 1}{100}$
$\Rightarrow S.I.=\$90$

So, $b=\$90$

Hence,
$a=4\%$ and $b=\$90$