Question 1043235
You have to start with the definition of average speed
It is: [ total distance ] / [ total time ]
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The total distance is twice around the track = {{{ 2 }}} mi
So far, using the definition, I have:
{{{ 60 = 2 / t }}}
where {{{ t }}} = total time
{{{ 60t = 2 }}}
{{{ t = 1/30 }}} hr
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For the 1st mile:
{{{ 1 = 40*t[1] }}}
{{{ t[1] = 1/40 }}} hr
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His time for the 2nd mile is:
{{{ 1/30 - 1/40 = 4/120 - 3/120 }}}
{{{ 1/30 - 1/40 = 1/120 }}}
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Let {{{ s }}} = his speed for the 2nd mile
{{{ 1 = s*(1/120 ) }}}
{{{ s = 120 }}}
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He needs a speed of 120 mi/hr for the 2nd mile
in order to average 60 mi/hr for the 2 miles.
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check my math also