Question

A car travels first 50 km with a constant speed of 30 km/h and next 40 km with a constant speed of 60 km/h . Caculate the average speed .

Answer 1

distance 1 = 50km
speed1 = 30km/h
time taken = distance /speed
= 50/30= 5/3 h
distance 2 = 40km
speed 2 = 60km/h
time taken = distance / time
= 40/60
= 2/3 h
average speed= total distance/total time taken
= (50+ 40)÷ (5/3)+ (2/3)
= 90 ÷ (7/3)
= 270/7
= 38.67km/h

Answer 2

Answer:

S1=50km

V1=30km/h

t=distance/time

=50/30=5/3h

S2=40km/h

V2=60km/h

time taken =distance /time

=40/60

=2/3h

avg. speed =total time /total time taken

=(50+40)÷(5/3)+(2/3)

90÷(7/3)

270/7=38.67km/h