forum.texasmath.org

by **redhawk2015** » Tue Apr 10, 2012 6:49 pm

My first ever 200 (228), so the practice is helping.

http://texasmath.org/DL/UIL2012C.pdf

A few questions:

#37: Converted the roll length into centimeters...is this a scaling problem? What do I do next?

#38: Is there a formula for this?

#46: Is this another scaling problem? Or do I "knead" to know the formula for surface area of a doughnut?

#47: I have a TI-84+. Is there an option for Inverse Regression, or is there another way to do this?

by **007math** » Tue Apr 10, 2012 7:41 pm

XD I couldn't help smile at that pun.

#46: You don't know the formula for surface area of donut? I swear this was basic elementary school stuff. $\displaystyle SA = \frac{ \pi (r_1^2 + r_2^2 - r_1 r_2)}{\sqrt{r_1^2 + r_2^2}}$ where r_1 is smaller radius and r_2 is bigger radius. Read on-->

Ok, that was a joke. It is one of those scaling problems. $\displaystyle \frac{12}{14^3} = \frac{2}{x^3}$ ; solve for x.

by **BlasianAsian** » Tue Apr 10, 2012 8:50 pm

Oh my god. I'll never be able to eat a donut the same ever again. D=

by **Shawn** » Wed Apr 11, 2012 2:06 pm

37) I would use linear regression
x(0,100)

by **Shawn** » Wed Apr 11, 2012 2:13 pm

47) Just manipulate your independent variable.
So for example the first entry would be:
x=1/11.7^2

Continue this and do the same with the given to get the appropriate y value.
If you don't understand let me know.

by **smeag** » Wed Apr 11, 2012 4:01 pm

ok, is there a format for questions 36-38? (ex. trajectory, scaling, etc.)

by **Shawn** » Wed Apr 11, 2012 5:20 pm

To the best of my knowledge, no. But, just as I stated on your "how to get to 300" thread, the questions recycle, so in theory yes. There are only so many types of questions covered. I am going to try to do the physics problem now (it has been awhile).

by **Shawn** » Wed Apr 11, 2012 5:58 pm

38) Talk about over thinking....
Start by finding height of ramp
$H_{ramp}=80*sin(20)$
$H_{ramp}=27.361611$
Now apply kinematics change in height equation.
$Y_{change}=v_{initial}*t+1/2*a*t^2$
-27.361611=55*22/15*sin(20)*t+1/2*-32.17*t^2