Atruck travels for 4 hours at an average speed of 42 miles per hour. how much longer must the truck travel at an average speed of 55 miles per hours so that the average speed for the total trip will be 50 miles per hour?

4 * 42 + 55 * x / ( 4 + x ) = 50.

The answer of x comes out to be 6.4. Which means that the truck will have to travel around 6.4 miles at an average speed of 55 miles to make it 50.

Well to understand how i constructed its equation is very simple. I equated the total average speeds answer to 50 and just calculated the average speeds with the help of algebra where x is the number of miles at 55 mph.

answer is 67%

step-by-step explanation:

44

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