SOLUTION: Mr Lim drove at 70 km per hour for 1 hour and 30 minutes. He then drove another 55 km. if his average speed for the whole journey was 80 km per hour, what was his speed for the 55

Question 712079: Mr Lim drove at 70 km per hour for 1 hour and 30 minutes. He then drove another 55 km. if his average speed for the whole journey was 80 km per hour, what was his speed for the 55 km journey?
Answer by Menjax(62) (Show Source): You can put this solution on YOUR website!
speed = distance/time
70=dab/1.5 (distance from a to b devided by an hour and a half)
Dab = 105km
Dbc = 55km
Sab = 70 (speed from a to b)
Total speed average = 80
Total distance = 160
Let x = total time
80 = 160/x
x = 2
speed = distance/time
SBC = 55/0.5
SBC = 110kmph

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