Question

A car travels 30km at a uniform speed of 40km/h and the next 50km at a uniform speed of 20 km/h. Find the average speed of the car.

Answer 1

Hey

Avg. speed = total distance/ total time taken

(a) d = 30 km ; s = 40 km/h

t = ? t = d/s = 30/40 = 3/4 h

(b) d = 50 km ; s = 20 km/h

t = d/s = 40/20 = 2 h


Avg. speed = total distance/ total time taken

 total distance = 30 + 50 = 80 km

total time = 3/4 + 2/1 = 11/4

Avg s = 80/ (11/4)

= (80/11) 4

= 29.1 Km/h

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Hope this helps!