A riverboat can travel downstream from Port A to Port B at 20mph.?

Question

It can travel upstream from Port B to Port A at 15 mph. If it takes 5 hours longer to go upstream than downstream, what is the distance between ports A and B??

this one as stumped me...im not sure how to work it out

Answer 1

get out the tape measure

Answer 2

This question sounds like a school book question so I am not going to give you the answer, but I will help you work it out.  If the boat can go 20 mph downstream and only 15 mph upstream then the difference is 5 mph.  That much I am sure you have figured out.  You now need to figure out the average between the two.  15 + 20 = 35.  35 divided by 2 = 17.5.  The average now gives you the speed of the boat through the water only, and not the speed over ground.  With a speed of 20 mph downstream and the speed of only 15 upstream, then the river must be flowing at a speed of 2.5 mph.  The boat is going 17.5 mph through the water and the water is helping it go faster downstream by adding the other 2.5 mph.  The boat has to fight the water speed going upstream.  The speed through the water is still 17.5 but it is fighting the river flow of 2.5 mph, so the boat speed over ground is 15 mph.  For every hour going downstream the boat gains 2.5 miles and for every hour upstream it looses 2.5 miles.  I hope this helps.

Answer 3

Just do your homework yourself and quit asking people on Yahoo to do it for you.lol