Question

A train covers the first 16 km at a speed of 20 kmph another 20 km at 40 kmph and the last 10 km at 15 kmph .find the average speed for the entire journey

Answer 1

avg vel=total disp/total time
=
$\frac{16 + 20 + 10}{ \frac{16}{20} + \frac{20}{40} + \frac{10}{15} }$
$= \frac{46}{ \frac{4}{5} + \frac{1}{2} + \frac{2}{3} }$
$= \frac{46 \times 30}{24 + 15 + 20}$
$= \frac{46 \times 30}{59}$
=23.38 kmph