Question 183983
It takes Mary 30 minutes to walk uphill 1 Km from her home to school, but it
 takes her only 10 minutes to walk from school to home along the same route.
 What is her average speed, in Km/hr, for the round trip?
:
Round trip dist = 2 km
:
Change the times to hrs:
30/60 = {{{3/6}}} hr
10/60 = {{{1/6}}} hr
:
Total time = {{{4/6}}} hr
:
Speed = {{{dist/time}}}
When dividing, invert the dividing fraction and multiply:
2 * {{{6/4}}} = {{{12/4}}} = 3 km/h is the average speed
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