SOLUTION: A boat sails downstream 36 miles and then returns upstream against the current. The downstream trip took 3/4 of an hour less than the upstream trip. If the speed of the current is

Click here to see ALL problems on Travel Word Problems

Question 1168102: A boat sails downstream 36 miles and then returns upstream against the current. The downstream trip took 3/4 of an hour less than the upstream trip. If the speed of the current is 4 mph, calculate the speed of the boat in calm water and the time of each trip. (20 mph, 1.5h downstream, 2.25 upstream)
Found 2 solutions by Boreal, solver91311:
Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
trip downstream at s+4 mph so 36/(s+4) hours
upstream at s-4 mph (s-4) so 36/(s-4)
we know that the second is (3/4 hour) more than the first
so 36/(s+4)+(3/4)=36/(s-4)
clear fractions
36(s-4)+(3/4)*(s^2-16)=36(s+4)
36s-144+(3/4)s^2-12=36s+144
(3/4)s^2-156=144
(3/4)s^2-300=0
s^2-400=0
s=20 mph only positive root.
24 mph downstream 1.5 hours to go 36 miles
16 mph upstream and takes 2.25 hours

Answer by solver91311(24713) (Show Source):
You can put this solution on YOUR website!

So if you know the answer, you must know how to work the problem. What do you want from us?

John

My calculator said it, I believe it, that settles it

I > Ø