1. A person wants to make an rectangular enclosed play pen using 60 meters of fence. One of the sides is against the house (thus, not requiring any fencing). What are the dimensions of the play pen to get the maximum area?
2. A boat can go 12 mph in calm water. If the boat goes down a river 45 miles and back up the river 45 miles it takes him 8 hours. What is the current of the river?
2007-12-16 08:54:50 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
the current of the river is 4 mph
x1*t1=45 m
x2*t2=45 m
x1+x2=24 mph
t1+t2=8 h
2007-12-20 02:45:15 · answer #1 · answered by Darko X 1 · 0⤊ 0⤋
first one is a rectangle 15 X 30 meteres in demensions. The area being 450 SQM
I can't get the second one. It's been over 20 years since I've done math. But I seem to be missing an equation. I have an extra variable which can't solve for.
I've got it as far as X=6/ (8-2Y)
Where X is the speed of the river and Y is the time to go down the river.
Please post the answer to the second if no one gets it.
2007-12-16 17:27:09 · answer #2 · answered by Almost freeee 3 · 0⤊ 0⤋
1) 60 meters divided by 3 sides of the house = 20 meters
20 meters per side.
a square is a rectangle so this is correct!
2007-12-16 17:04:40 · answer #3 · answered by kim 4 · 0⤊ 0⤋
1. If one of the walls is against a house, than you only have to divide 60 by 3...where you will get 20, which means that each wall is 20 meters long.
I hope that helps!!
-note: nevermind; that would make a square...I will figure this out! lol
2007-12-16 17:00:02 · answer #4 · answered by Lizard_Luver 5 · 0⤊ 0⤋
I don't think the boat-current problem can be solved with the available data.
D=rt
90=r*8
R=90/8 = 11.25mph
The up-river current is cancelled by the down-river current no matter how fast it is. I'd like to know if I'm wrong.
2007-12-16 17:25:24 · answer #5 · answered by Ken 7 · 0⤊ 0⤋