A student walks from his house at 2km/h and
reaches his school late by 6min. Next day , he
increases his speed by
1km/h and reaches 6min before school time. How
far is the school from his house??
Answers
➢ Answer :
Total distance from house to school = 1.2 km
➢ Given :
Speed on first day = 2 km/h
Speed on second day = 3 km/h
Time taken on first day = 6 min after original time.
Time taken on second day = 6 min before original time.
➢ To Find :
Total distance from the student's house to his/her school.
➢ How To Find :
Let the original time be t.
▶ Case I :
Speed = 2 km/h
Time taken = t + 6 min
▶ Case II :
Speed = 3 km/h
Time taken = t - 6 min
Now, difference of time in the two cases :-
⇝ t + 6 - (t - 6) = 6 + 6 = 12 min
⇝ 12/60 hours.
____________________________
Now, Let the total distance covered be d.
Also, Time = distance/speed
∴ Time taken in the first case = d/2
Time taken in the second case = d/3
Also, d/2 - d/3 = 12/60 (difference in time is 12/60 hours)
⇝ 3d - 2d/6 = 12/60
⇝ d/6 = 12/60
⇝ 60d/6 = 12
⇝ 10d = 12
⇝ d = 12/10 = 6/5
⇝ d = 1.2
Hence, the school is 1.2 km far away from the student's house.