Question

On a track of 90km a train travels first 70 km at a speed of 50 km/hr what should be its speed for remaining distance so that on the entire journey average speed is 60 km/hr​

Answer 1

Answer:

$average \: speed \: = \frac{total \: distance}{total \: time \:taken }$

for 90 km,

$t = \frac{90}{60 \frac{km}{hr} }$

$= 1.5hr$

for 1st 70 km,

$t1 = \frac{70}{50 \frac{km}{hr} }$

$= 1.4hr$

for remaining 20 km,

$t2 = t - t1$

$= 1.5 - 1.4$

$= 0.1hr$

$speed = \frac{distance}{time}$

$= \frac{60}{0.1}$

$600 \frac{km}{hr}$