district 2 questions

[rcoker7]

Ok so on district 2 from this year, there's 2 answers I disagree with. I'm not sure what I did wrong

47- Dalia fires an arrow in an attempt to land the arrow at 20 yard increments. Her actual shots landed at 20, 38, 67, 82, 110. For what distance should she aim if she wants to land it at 150 yards.

ok so I found a regression for this and set it equal to zero, which gave me about 137. The answer is 164, which is what you would get if you plugged in 150 into the regression. This seems backwards to me, considering if she was trying to land the arrow at 150, she would aim at a lower value to account for her inaccuracy. The wording on this question is horrible, IMO.

50-(there was a cone and a sphere touching, with the height of the cone plus one radius equalling 216. You had to find the radius considering the total surface areas of the 2 figures are equal. See the test for a better visual).

I set up the equation 4*pi*r^2=pi*r^2+pi*r*sqrt(r^2+(216-r)^2) and my calculator gave me 56.4. The answer is 52.1. I have no idea where they got that.

Thanks in advance for any help anyone can provide.

[FabensMath]

I got the same thing for 47 when i took the test. I think it's backwards too.
I'll check the other one.

[FabensMath]

I checked it, got the same thing for the geometry...i'm sorry, that wasn't helpful. Also, keep in mind that there might be errors on the key, this is the first year I notice errors, like on region, there was one where apparently there was an extra parenthesis which could throw the problem off, not saying that this is one of them, just keep it in mind.

[rcoker7]

Thanks Miguel! I've noticed for some reason calculator always has the most errors on the key. I'm not really sure why.

[Shawn]

47) I think you are over thinking, it is a linear regression problem treat it as one. The value of 150 is the actual distance, so her aiming represents the y value as entered below.
[unparseable or potentially dangerous latex formula]
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[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
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[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
Since from your post you do not use an HP for L.R., the L.R. equation generated is
[unparseable or potentially dangerous latex formula]
Plugging in 150 for x
[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
50) Equation solve:
[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]
I will see where the keyed solution comes from and edit in a little while.

[rcoker7]

but according to the problem, the actual distances were the y values, and the attempted distances were the x values. the wording is very confusing :/

EDIT: nevermind, that's what you said too. I guess the wording in the end is what screwed me up.

[Shawn]

I can't get the keyed answer for 50. Either the key is wrong or I am missing something.

[calcguy]

I checked with Dr. Bourell. He said the key was wrong on 12G-47 and 12G-50. The correct answers are 137 and 56.4 so you're working the problems correctly.

[redhawk2015]

OK good...I had been getting those same two answers as well...