Question 263749
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How far upstream can a motorboat travel at 8 mi/hr and still return downstream at 12 mi/hr in a total time of 4 hr?
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Let distance, back and forth, be D
Then time taken to travel upstream, is {{{D/8}}}
Also, time taken to travel downstream, is {{{D/12}}}
We then get the following TOTAL-TIME equation: {{{D/8 + D/12 = 4}}}
                                                                                 3D + 2D = 96 ---- Multiplying by LCD, 24 
                                                                                          5D = 96
                                           Distance, back and forth, or {{{D = 96/5 = highlight(matrix(1,2, 19.2, miles)))}}}</font></font></font></b></pre>