Question

Abdul, while driving to school, computes the average speed for his trip to be 50 km h–1. On his return trip along the same route, there is less traffic and the average speed is 80 km h–1. What is the average speed for Abdul’s trip?
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Answer 1

Answer:

Let us assume that Abdul is travelling x kilometer distance while going to school.

Distance = Speed x Time

1)When it's average speed is 20 km/hr

x=v

1

×t

1

=20×t

1

2)When it's average speed is 30 km/hr

x=v

2

×t

2

=30×t

2

V

average

=

totaltimetaken

totaldistancetravelled

V

average

=

v

1

x

+

v

2

x

x+x

=

20

x

+

30

x

2x

=24 km h

−1

Answer 2

ANSWER

Let us assume that Abdul is travelling x kilometer distance while going to school.

Distance = Speed x Time

1)When it's average speed is 20 km/hr

x=v1×t1=20×t1

2)When it's average speed is 30 km/hr

x=v2×t2=30×t2

Verified answer!

Vaverage=totaltimetakentotaldistancetravelled

Vaverage=v1x+v2xx+x=20x+30x2x=24 km h−1