Question

A boy leaves his house at 9:30 am for his school. The school is 2km away and classes start at 10:00am .if he walks at the speed of 3km/h for the first km,at what speed should he walk the second km to reach just in time?

Answer 1

$speed \: \: s= \frac{d}{t}$
time taken to travel first 1km is
$\frac{1}{3} hr = 20minutes$
remaining time is 10 minutes
$10minutes = \frac{1}{6} hr$
remaining distance is 1km.
therefore the speed at which he should walk is
$\frac{1}{ (\frac{1}{6} )} = 6$
that is 6 km/hr