Question

A train moves from station A to station B covering a distance of 1800 km. If it covers first 900km at an average speed of 60 km/hr next 300 km at 75 km/hr , at what average speed should it cover the remaining distance so as to strike an average speed of 50 km/hr for the entire journey?

Answer 1

Dear Student ,
$$\begin{gathered} Hereinthiscase, \\ 50=\frac{1800}{{\displaystyle \frac{900}{60}}+{\displaystyle \frac{300}{75}}+{\displaystyle \frac{600}{v}}} \\ \Rightarrow 19+\frac{600}{v}=\frac{1800}{50}=36 \\ \Rightarrow \frac{600}{v}=36-19 \\ \Rightarrow v=\frac{600}{17}=35·3km/hr \end{gathered}$$

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