Question 405869
time = distance /speed

1 mile = 5280 feet
500 feet = 500/5280 miles

time while going = {{{(500/5280)}}}/{{{4}}} 

Time while returning ={{{(500/5280)}}}/{{{3}}}

Total time = {{{(500/5280)}}}/{{{4}}} + {{{(500/5280)}}}/{{{3}}}

Total time = {{{500/(5280*4)}}} + {{{500/(5280*3)}}}

Total time = {{{(500*3+500*4)/(5280*12)}}} 

Total time = 0.055 hours
...
speed = distance / time

speed = (1000/5280) / 0.055

Average speed of total trip = 3.44 mph