Answers

2015-06-09T14:25:55+05:30
D₁ = 5 Km
S₁ = 10 Km/h
t₁= D₁/S₁
= 5/10
= 1/2 hour  OR 30 minutes
D₂ = 5 Km
 [ same as D₁ because it is coming down by travelling the same distance]
S₂ = 20 km/h
t₂ = D₂/S₂
= 5/20
= 1/4 hour or 15 minutes
therefore , average speed = total distance / total time
                                      = (D₁ + D₂) / (t₁ +t₂)
= (5+5)/(3/4)
= 10*(4/3)
= 40/3
= 13.33 km/h
1 5 1
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