Question

if sushant ride his bicycle at the speed of 2 km /hr he reaches school late by 1 minute on increasing the speed by 2km/hr he reaches 5 minutes early find the distance between his school and his house

Answer 1

let the distance be x km and the time taken to reach the school at the speed of 2km/hr be (t+1)min
Atq
x/(t+1)=2km/hr=2/60km/min=1/30km/min
x=(t+1)/30----1)
x/(t-5)=4km/hr=4/60km/min=1/15km/min
x=(t-5)/15-------2)

On comparing 1) and 2)
(t+1)/30=(t-5)/15
=>t+1=2t-10
=>t=11min
putting this in 1)
x=12/30=2/5km=0.4km=400 m