Jan 2008 Math

<p>hey city birds...you got that right i think...the answer to the speed one was 30mph</p>

<p>i think i prob. got 2-3 wrong in math. i definitely know i got the speed one wrong and there's usually some simple slip up that gets me elsewhere.</p>

<p>theres no way it was 30, that's wayyyyyy too simple.</p>

<p>it can't be 30mph..if you think like the test makers...the hardest question in a section..won't just be average...then u think about it alittle.and realize ur going 20 miles an hour longer then ur going 40 miles an hour....so the average ...should be less then 30...</p>

<p>you multiply 20 by 10 and get 200 cuz thats what the speeds would add up to if you added up all the miles in the 10 mile stretch....then you multiply 40 by 10 and get 400, same reason...then you add them and divide by 20 miles and get 30... i'm 100% positive on that...ive been practicin those</p>

<p>w = x+y+z and it asked to find the average so wouldnt it be w/3?</p>

<p>you forgot the time part of the distance/rate/time equation griffon...</p>

<p>you guys were thinkin too much...i did a problem just like it for SAT prep</p>

<p>its the xiggi formula</p>

<p>2<em>r1</em>r2/(r1+r2)
2<em>40</em>20/(20+40)= 26.6 or 80/3</p>

<p>griffon i actually did that.</p>

<p>i realize how i did sooo many of these problems many times each to check. well i just hope 30 is somehow right but if not oh well.</p>

<p>mdawg : w/2</p>

<p>Carsonne, for the circle problem I did everything you did except I got sqrt 2 minus one (diameter of bigger circle is 1)/2</p>

<p>amirite?</p>

<p>how is it w/2</p>

<p>it was askin for the average speed for the 20 miles...not for the time it took for the 20 miles...i seriously am sure on that one</p>

<p>its was a number 18 out of 18 questions in that section...ur supposed to think pretty deep...because most people are supposed to get it wrong...</p>

<p>what was the answer for the lf(x)l question? was the graph a typical absolute value curve (V shaped) or was it a positive line, since the absolute value was only for the f(x) value, instead of the x value?</p>

<p>nvm, I figured out that I was wrong... dang it!</p>

<p>well the legs are 2 each so hypotenuse is two root 2... so shouldnt it be TWOsqrt2 - 1
divided by two which = root2 / 2?</p>

<p>that formula gives you average speed for one hour which is what the question asks for</p>

<p>Prothero...yeah i think you're right...thats what I got...but i dont think thats why</p>

<p>i understand how u guys came up with 26.7, but the question wasn't the average velocity with respect to time travelled. It was the average velocity with respect to distance travelled (20 miles).</p>

<p>wait wut problem matt just told me about 26.6666 whats that to whats problem</p>

<p>arg, think I read it as 1 each</p>