2. Abdul while drivir.g to school computes the average speed for his trip to
be 20km per hour on his return trip along the same route there is less
traffic and average speed is 30km per hour what is the average speed for
Abdul's trip?
Answers
Given :
• Average speed while going to school = 20 km/h
• Average speed while returning from school = 30 km/h
To find :
• Average speed for Abdul's trip
Solution :
Let the distance traveled by Abdul from home to school = s km
→ Time taken to reach the school = t1 seconds
For Return journey,
→ Abdul cover distance = s km
→ Time = t2 seconds
∴ Average speed for forward journey [home - school] = Total distance ÷ Total time
Substituting the values :-
→ 20 km/h =s/t1
∴ t1 = s/20 h ------eq(1)
Average speed for backward journey[school -home] = Total distance ÷ Total time
Substituting the values :-
→ 30 km/h =s/t2
→ t2 = s/30h -----eq(2)
Average distance for entire journey = Total distance ÷ Total time
Substituting the given values :-
→ (s+s)/[s/20 +s/30]
→ 2s/s[1/20+1/30]
→ 2 × 20 × 30/50
→ 24 km/hr
Therefore, the average speed for Abdul's trip = 24 km/h