Question 895946
The distance doesn't matter, and can
be any number, so I'll say it is {{{ 6 }}} miles
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Going upstream:
{{{ 6 = 3*t[1] }}}
{{{ t[1] = 2 }}} hrs
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Going downstream:
{{{ 6 = 6*t[2] }}}
{{{ t[2] = 1 }}} hr
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Average speed is always:
( total distance ) / ( total time )
{{{ ( 6 + 6 ) / ( 2 + 1 ) }}}
{{{ 12/3 = 4 }}}
The average speed is 4 mi/hr