Question 966545
{{{ s }}} = speed of kayak in still water
{{{ c }}} = the speed of the current
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Going upstream:
(1) {{{ 12 = ( s - c )*3 }}}
Going downstream:
(2) {{{ 12 = ( s + c )*2 }}}
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(1) {{{ 3s - 3c = 12 }}}
(2) {{{ 2s + 2c = 12 }}}
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(1) {{{ s - c = 4 }}}
(2) {{{ s + c = 6 }}}
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{{{ 2s = 10 }}}
{{{ s = 5 }}}
and
(1) {{{ s - c = 4 }}}
(1) {{{ 5 - c = 4 }}}
(1) {{{ c = 1 }}}
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The speed of the current is 1 mi/hr
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The average speed of the kayaker is:
[ total distance ] / [ total time ]
{{{ ( 12 + 12 ) / ( 3 + 2 ) }}}
{{{ 24/5 = 4.8 }}} mi/hr