Question 1114525
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a)  The person rode 3 miles in total.


    For the 1-st mile he spent  {{{1/10}}}  of an hour.


    For the 2-nd mile he spent  {{{1/8}}}  of an hour.
    

    For the 3-rd mile he spent  {{{1/6}}}  of an hour.


    In all, he spent  {{{1/10}}} + {{{1/8}}} + {{{1/6}}} = {{{12/120 + 15/120 + 20/120}}} = {{{47/120}}}  of an hour.


    The average speed = {{{distance/time}}} = {{{3/((47/120))}}} = {{{(3*120)/47}}} = 7.66 miles per hour.
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Solved.