Question 947446
{{{ 20/60 = 1/3 }}} hrs
{{{ 30/60 = 1/2 }}} hrs
Let {{{ s }}} = the speed of the boat in still water in mi/hr
Let {{{ c }}} = the speed of the current in mi/hr
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Going downstream:
(1) {{{ 16 = ( s + c )*(1/3) }}}
Going upstream:
(2) {{{ 16 = ( s - c )*(1/2) }}}
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(1) {{{ s + c = 48 }}}
(2) {{{ s - c = 32 }}}
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Add the equations
{{{ 2s = 80 }}}
{{{ s = 40 }}}
and
(1) {{{ 40 + c = 48 }}}
(1) {{{ c = 8 }}}
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The speed of the boat in still water is 40 mi/hr
check:
(2) {{{ s - c = 32 }}}
(2) {{{ 40 - 8 = 32 }}}
(2) {{{ 32 = 32 }}}
OK