Question 695724
Let {{{ s }}} = her speed rowing in still water
Let {{{ c }}} = the rate of the current
{{{ s - c }}} = the speed of the boat going upstream
{{{ s + c }}} = the speed of the boat going downstream
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Her equation for going upstream:
(1) {{{ 6 = ( s - c )*3 }}}
Her equation for going downstream:
(2) {{{ 6 = ( s + c )*2 }}}
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(1) {{{ 6 = 3s - 3c }}}
(1) {{{ 2 = s - c }}}
and
(2) {{{ 6 = 2s + 2c }}}
(2) {{{ 3 = s + c }}}
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Add (1) and (2)
(1) {{{ 2 = s - c }}}
(2) {{{ 3 = s + c }}}
{{{ 5 = 2s }}}
{{{ s = 2.5 }}}
and,since
(1) {{{ 2 = s - c }}}
(1) {{{ 2 = 2.5 - c }}}
(1) {{{ c = .5 }}}
Paula rows 2.5 mi/hr is still water
The speed of the current is .5 mi/hr
check answers:
(1) {{{ 6 = ( 2.5 - .5 )*3 }}}
(1) {{{ 6 = 2*3 }}}
and
(2) {{{ 6 = ( 2.5 + .5 )*2 }}}
(2) {{{ 6 = 3*2 }}}
(2) {{{ 6 = 6 }}}
OK