Abdul, while driving to school computes the average speed for his trip to be 20kmph. On his return trip, along the same route there is less traffic, and the average speed is 30 kmph. What is the average speed of his trip?
Answers
Explanation:
Abdul, while driving to school, computes the average speed for his trip to be 20 km h-1. On his return trip along the same route, there is less traffic and the average speed is 30 km h-1.
We need to find
The average speed for Abdul’s trip
Solution
Let us take the following assumptions for calculating the average speed for Abdul’s trip
As per given data in the question
Average speed from home to school v1av = 20km h-1
Average speed from School to Home v2av = 30km h-1
Our assumptions
The distance Abdul commutes while driving from Home to School = S
Let us assume time taken by Abdul to commutes this distance = t1
Distance Abdul commutes while driving from School to Home = S
Let us assume time taken by Abdul to commutes this distance = t2
Also we know that
The time taken from Home to School t1=S/v1av
Similarly Time taken from School to Home t2=S/v2av
Total distance
Total distance from home to school and backward = 2S——-(i)
Total time taken from home to school and backward (T)=S/20+S/30———-(ii)
Formula
Speed = Distance / Time
Therefore,
Average Speed(Vav)for covering total distance (2s)=Total Distance/Total Time
So from equations (i) and (ii) we get,
Average Speed(Vav) =2S/(S/20+S/30)
=2S/[30S+20S)/600] =1200S/50S
=24kmh-1
Final Answer
The average speed for Abdul’s trip = 24kmh