Anyone Wanna Help Me Out with some Math?

[DGH94]

And after looking at the first one, I made a rookie mistake there.
It takes pipe A, running alone, 18 hours to fill the tank. It takes both pipes, running together, 9.9 hours to fill the tank. How long does it take pipe B, running alone, to fill the tank?
-----
A DATA:
time = 18 hrs/job ; rate = 1/18 jobs/hr
--------------------------------------------
A/B DATA:
time = 9.9 hrs/job ; rate = 1/9.9 job/hr
--------------------------------------------
B DATA:
time = x hrs/job ; rate = 1/x job/hr
----------------------------------------
Equation:
rate + rate = together rate
1/18 + 1/x = 1/9.9
---
9.9x + 9.9*18 = 18x
8.1x = 9.9*18
x = 22 hrs (time required by the B pipe to fill the tank)

Give me some slack, schools out. xD

[Random_Guy]

I'm too good-looking to know these stuff.

[Kamazar]

Originally Posted by DGH94

And after looking at the first one, I made a rookie mistake there.
It takes pipe A, running alone, 18 hours to fill the tank. It takes both pipes, running together, 9.9 hours to fill the tank. How long does it take pipe B, running alone, to fill the tank?
-----
A DATA:
time = 18 hrs/job ; rate = 1/18 jobs/hr
--------------------------------------------
A/B DATA:
time = 9.9 hrs/job ; rate = 1/9.9 job/hr
--------------------------------------------
B DATA:
time = x hrs/job ; rate = 1/x job/hr
----------------------------------------
Equation:
rate + rate = together rate
1/18 + 1/x = 1/9.9
---
9.9x + 9.9*18 = 18x
8.1x = 9.9*18
x = 22 hrs (time required by the B pipe to fill the tank)

Give me some slack, schools out. xD

Thanks, DGH. This clears it up. I eventually found the first one out on my own. Simple proportion

[The Bat Outta Hell]

So thaaaat's why I failed math.

[DGH94]

Originally Posted by Kamazar

Thanks, DGH. This clears it up. I eventually found the first one out on my own. Simple proportion

Np. I took Alg2AP this year and got an A, so I SHOULD know this. xD

[Random_Guy]

How do I find the acute angle between y=2x and y=-2x?

[Electric_Shaman]

Originally Posted by Random_Guy

How do I find the acute angle between y=2x and y=-2x?

Well you'd have to look for it I guess. When was the last time you saw it? And you've checked it's not in any of your pockets right?

[DGH94]

Originally Posted by Random_Guy

How do I find the acute angle between y=2x and y=-2x?

If you're serious, what you want to do is draw a third line to make a right triangle. It should be the reciprocal of one of the lines if I remember correctly. Then find the distance of two of the sides of the triangle, and then use trig to find the angle needed.
BUT, the two equations you gave me don't form an acute angle, they form an angle of 120 degrees, an obtuse angle. So technically you're question is obsolete or I'm a complete retard.

[wootbean]

Originally Posted by DGH94

If you're serious, what you want to do is draw a third line to make a right triangle. It should be the reciprocal of one of the lines if I remember correctly. Then find the distance of two of the sides of the triangle, and then use trig to find the angle needed.
BUT, the two equations you gave me don't form an acute angle, they form an angle of 120 degrees, an obtuse angle. So technically you're question is obsolete or I'm a complete retard.

then there's also an angle of 60deg

[Random_Guy]

Nvm.