dean5150

xlostinwords- I don't remember the answer exactly, but I know you drew a right triangle with 6 inches as one leg, the radius as the other leg, and then the hypotenuse was everything within a certain number. then use the radius of the circle to find the area.

Does anyone know how to explain the last one? was it .9 or .7?

duchess26200

I got 108pi=339.3

duchess26200

and the last one I got .923; I've explained it before, just look at previous pages.

sportsfreak26

I thought for the last question, the answer was 0.

dabulls

where are you guys getting these scaled scores from???

my pr practice book says i need to get a perfect to get a 800 and a 41 raw is a 690

what do u really think my score is if a omitted 4 and got 5 wrong

SparklingJuice

^ Probably 750 or something like that.

I really wanted to get 800, I think I missed it though.. I have 5 wrongs and 1 blank so far... And there is like 1% chance I get all of the rest right.

I made so many stupid errors.

How is that question (-2, -3)? It's reflecting (3,2) with y=-x, right? I thought it would be (-3,-2).

UnleashedFury

That's probably around a 760.

xlostinwords

It's ok sparkling juice i got the same thing.

sportsfreak26

Yeah I thought it was (-3, -2) as well.

duchess26200

Transformations in Coordinate Geometry - Reflection in a Line
If you scroll down a little bit, it says that a point (x,y) reflected over y=-x is (-y,-x). Since the original was (3,2), then it would be (-2,-3).

niloy.ghosh518

ok everyone. chill out. the math curves are usually extremely easy. i skipped 4 on purpose last year, and still got 800 :P Unleashed fury, 4 omit and 5 wrong is probably 750-760ish

Nile

Another explanation for that reflecting (3,2) across y=-x

remember that (3,2) is a coordinate of (x,y)
When we're reflecting this point across the line y=-x we're saying that the y value is -x and conversely x is -y

(3,2) => (x,y)
When reflected across y=-x
(x,y) => (-y,-x)
therefore
(3,2) => (-2,-3) when reflected across y=-x

For the average running speed question.
I think the question was person x runs 40 km/hr in the first half and 80km/hr in the second half. The total distance is 20km.
First step is to find the total time to run that distance.
First half
d=rt => 10=40t => t=1/4 hr.
d=rt => 10=80t => t=1/8 hr.
T=t1+t2=1/4+1/8=3/8 hr
so the average speed of the entire trip is 20/(3/8) = 53.33 km/hr

Nile

@goodatlife+fivewinks

The correct answer was the one with 4 uniform bars.
Standard deviation is a measure of how spread out the data is.
If there is only one bar, the other data points are 0. So there is a spread from the mean....meaning there's a standard deviation > 0.
If all the bars are uniform, there's 0 spread from the mean so standard deviation is 0.

duchess26200

No; standard deviation is calculated by the following steps: 1) Find mean of data 2) Find difference between each datum and the mean 3) Square all the individual differences 4) Average squares of differences 5) Square root all.

If we had one bar, the set of data would be 80, 80, 80,...80 (example). Therefore, the mean would be 80, the individual differences would be 0, do everything else to it, and you'd still get 0.

WantIvy

yes, the standard deviation one was A, the one with one big bar.