Question 827967
Average speed is always:
( total distance ) / ( total time )
Let {{{s}}} = her average speed for the last hr
Her total time was {{{3}}} hrs
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For 1st 2 hrs:
distance = {{{ 85*2}}}
distance = {{{ 170 }}}
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For next hr:
distance = {{{ s*1 }}}
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Average for the whole trip:
{{{ 75 = ( 170 + s ) / 3 }}}
{{{ 225 = 170 + s }}}
{{{ s = 55 }}}
Her average speed for the last hr was 55 km/hr