Question 919592

A truck with a heavy load drove from Boston to New York at 45 mph. After unloading, it returned from New York to Boston at a speed of 65 mph. What was its average speed for the whole trip?
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Let distance from New York to Boston, and vice-versa, be D
Then, time taken to travel from Boston to New York is: {{{D/45}}}
Also, time taken to travel from New York to Boston is: {{{D/65}}}
Total time taken for entire trip: {{{D/45 + D/65}}}______{{{(13D + 9D)/585}}}______{{{22D/585}}}

Average speed: {{{(Total_Distance)/Total_Time}}}
Average speed: {{{2D/(22D/585)}}}
Average speed: {{{(2D/1) * (585/(22D))}}}
Average speed: {{{cross(2D) * 585/11cross(22D)}}} ------ Canceling 2D in numerator and denominator
Average speed: {{{585/11}}}, or {{{highlight_green(highlight_green(53&2/11)))}}} mph