Question

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

Answer 1

HI!!

HERE IZ UR ANSWER.

Distance to school = 2 km

Time remaining = 30 minutes or 1/2 hrs.

So, speed with which he should walk constantly with would be = 2/0.5

as, Speed = dist / time

So, his constant speed must be 4km / hr.

But he walked 1st km wid speed of 3 km/h.
So, he must increase his speed to arrive on time.

time taken to complete 1st km,

speed = 3km / h
distance = 1 km
let t be time

3 = 1/t
t = 1/3 hrs.

So time remaining would be,

1/2 - 1/3 = 1/6

So, speed for final km would be

distance = 1km
time = 1/6 hr

speed = 1÷1/6
speed = 6 km/hr.

So he must walk with speed of 6 km/h to reach on correct time.

HOPE IT HELPS!!