Question

A 60- litre tank was full of oil. Sam used 40% of it and poured the rest into a 40 litre tank.
(1) What percent of the 40-litre tank was filled with oil ?
(2)If Sam used 3 litre of oil daily, what percent of oil in the 40 litre tank would be used in 10 days?

Answer 1

$$\begin{gathered} \mathrm{Total}\mathrm{quantity}\mathrm{of}\mathrm{oil}=60\mathrm{l} \\ \mathrm{Quantity}\mathrm{of}\mathrm{oil}\mathrm{used}=40\%\mathrm{of}60\mathrm{l}=\frac{40}{100}\times 60=24\mathrm{l} \\ \mathrm{Quantity}\mathrm{of}\mathrm{oil}\mathrm{left}=60-24=36\mathrm{l} \\ \mathrm{Now},\mathrm{the}\mathrm{remaining}\mathrm{oil}\mathrm{was}\mathrm{poured}\mathrm{into}40\mathrm{l}\mathrm{tank}. \\ \left(\mathrm{a}\right). \\ \mathrm{Percentage}\mathrm{of}40\mathrm{l}\mathrm{tank}\mathrm{filled}\mathrm{with}\mathrm{oil}=\left(\frac{36}{40}\times 100\right)\%=90\% \\ \left(\mathrm{b}\right). \\ \mathrm{Quantity}\mathrm{of}\mathrm{oil}\mathrm{used}\mathrm{daily}=3\mathrm{l} \\ \mathrm{Quantity}\mathrm{of}\mathrm{oil}\mathrm{used}\mathrm{in}10\mathrm{days}=10\times 3=30\mathrm{l} \\ \mathrm{Percentage}\mathrm{of}\mathrm{oil}\mathrm{used}\mathrm{from}\mathrm{the}40\mathrm{l}\mathrm{tank}=\left[\frac{30}{36}\times 100\right]\%=\left(\frac{250}{3}\right)\% \end{gathered}$$