Question 938999
Convert {{{ 20 }}} sec to minutes
{{{ 20/60 = 1/3 }}} min
Convert minutes to hrs
{{{ (1/3)*60 = 1/180 }}} hrs
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Find vehicle b's head start in miles
{{{ d[1] = 15*(1/180) }}}
{{{ d[1] = 1/12 }}} mi
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Start a stopwatch when vehicle a leaves
Let {{{ t }}} = time in hrs on the stopwatch
when a get to the {{{ 1/4 }}} mi mark
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a's equation:
{{{ 1/4 = 30t }}}
{{{ t = 1/120 }}} hrs
{{{ t = ( 1/120 )*3600 }}}
{{{ t = 30 }}} sec
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Start a different stopwatch when vehicle a leaves
Let {{{ t[1] }}} = time in hrs on the stopwatch
when b gets to the {{{ 1/4 }}} mi mark
b's equation:
{{{ 1/4 - 1/12 = 15t[1] }}}
{{{ t[1] = ( 3/12 - 1/12 ) / 15 }}}
{{{ t[1] = ( 1/6 )/15 }}}
{{{ t[1] = 1/90 }}} hr
{{{ t[1] = ( 1/90 )*3600 }}}
{{{ t[1] = 40 }}} sec
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a arrives at the 1/4 mi mark first, and
beats b by {{{ 40 - 30 = 10 }}} sec