SOLUTION: : for the first 1.5 hours of a 91 km journey, the average speed was 30km/hour. if the average speed for the remainder of the journey was 23 km/hour, calculate the average speed for

Question 663119: : for the first 1.5 hours of a 91 km journey, the average speed was 30km/hour. if the average speed for the remainder of the journey was 23 km/hour, calculate the average speed for the entire journey.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
for the first 1.5 hours of a 91 km journey, the average speed was 30km/hour.
if the average speed for the remainder of the journey was 23 km/hour, calculate the average speed for the entire journey.
:
Find the distance driven at 30 km/hr: 30*1.5 = 45 km
then
91 - 45 = 46 km driven at 23 km/hr
and
46/23 = 2 hrs is the time at 23 km/hr
:
let a = the av speed for the entire journey
:
Write a time equation; time = dist/speed
:
30km/hr time + 23km/hr time = 91km time
1.5 + 2 =
3.5 =
multiply equation by a:
3.5a = 91
a = 91/3.5
a = 26 km/hr av speed for the entire journey
:
Did all this make sense to you, any questions? C

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