A group of friends are going on a day out to Project Hilsha. They divided their route into 3 equal parts, and planned on maintaining an average speed of 68 km/h on their way to their destination. Their speed for the first and second part were 72 km/h and 88 km/h respectively. What speed should they maintain for the third part of their journey if they are to achieve their target average speed?
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Step-by-step explanation:
let the speed in third part be x km/h
mean = (72+88+x)/3 = 68
160+x = 68*3
160+x = 204
x = 204-160=44
Answered by
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Answer: 68km/h
Step-by-step explanation: We have to find the harmonic mean here because speed is a proportion of two units, distance and time.
The equation---
3/{(1/72)+(1/88)+(1/v)}= 68
Which yields, v = 68km/h
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