A truck with a heavy load drove from Boston to New York at 50 mph. After dropping of the load, it returned from New York to Boston with a speed of 70 mph. What is the average speed of the truck for the whole trip?

Respuesta :

Answer:

175/3 or 58.333...

Step-by-step explanation:

This is fairly complicated but I will try to make it as simple as possible. I also apologize in advance for how impossible it is to make fractions look like fractions. I also had to insert a bunch of unnecessary parentheses just because the fractions that I can make are relatively inaccurate.

The distance between 2 cities can be represented as d.

Time is d/r if r is rate, so B->NY=d/50

Similarly,NY->B is d/70

Obviously the average speed is 2d/(d/50+d/70), this is just an average time

Now just remove the d and get (d/d)*2/(1/50+1/70)

You can now multiply by the LCM/LCM, which is 350/350.

After calculating you will get 700/12 which is 58.333...(This is how to enter into your RSM browser) Hope this helps. Sorry it is so late.

The  average speed of the truck for the whole trip is 58mph.

Average speed

rate = 50 mph

distance = x miles

time = d/r = x/50 hrs

rate = 70 mph

distance = x miles

time = d/r = x/70 hrs

Average speed = (total distance)/(total time) = 2x/(x/50 + x/70)

Average speed= (2x)/(70x + 50x)/(50×70)

Average speed= (2x)/[120x/3500]

Average speed= 2/(0.034)

Average speed= 58 mph

Inconclusion the  average speed of the truck for the whole trip is 58mph.

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