Management Aptitude Test Sep 2011 Paper

(2) Given, ₹ 20 is the TD on ₹ 260 due after certain time.
If time and rate be T and R respectively, then
TD = $\frac{\mathit{A}\mathit{m}\mathit{o}\mathit{u}\mathit{n}\mathit{t}\times \mathit{R}\times \mathit{T}}{100+\left(\mathit{R}\times \mathit{T}\right)}$
⇒ 20 =$\frac{260\times \mathit{R}\mathit{T}}{100+\mathit{R}\mathit{T}}$
⇒ 100 + RT = 13RT
⇒ 12RT = 100
⇒ RT = $\frac{100}{12}=\frac{25}{3}$
In second condition, rate is same but time is half, then
R ⋅ $\frac{\mathit{T}}{2}=\frac{25}{3}\cdot \frac{1}{2}=\frac{25}{6}$
Now, required TD = ₹ $\frac{260\times 25}{\left(100+\frac{25}{6}\right)\times 6}$
= ₹ $\frac{260\times 25\times 6}{625\times 6}$
= $\frac{260}{25}$ = ₹ 10.40