A logging barge on the Mississippi river travels 24 miles up stream in 3 hours. The return trip takes the barge only 2 hours. Find the rate of chang of the barge in still waters.

Question

nurali · Answer

Speed is distance divided by time. 
Going upstream slows you down by the speed of the river 

$$V _{barge}-V _{river}=\frac{ 24 miles }{ 3hours }=8mph$$
Going downstream you go faster: 
$$V _{barge}+V _{river}=\frac{ 24 miles }{ 2hours }=12mph$$

If you add the two equations, Vriver cancels and you get: 

$$2V _{barge}=20mph$$
$$V _{barge}=10mph$$

anonymous · Answer

thankyou uvu