Question

A fast train covers $320km$ in $3hrs$and $20minutes.$How much time will it take to cover a distance of $90km$?

Answer 1

By unitary method:

Time required to cover $320km=3hours20minutes$

Time required to cover $320km=3\times 60+20=180+20=200$minutes

Time required to cover $1km=$$\frac{200}{320}=\frac{20}{32}$minutes

Time required to cover $$\begin{gathered} 90km=\frac{20}{32}\times 90 \\ =0.625\times 90 \\ =56.25minutes \end{gathered}$$

Time required to cover $90km=56.25minutes$