<p>I figure this might be useful, for those of us trying to get high scores. If you have a question that you can't answer (math question, grammar question, sentence completion etc...), or if you just have a hard question, post it here and hopefully someone will respond with an explanation.</p>
<p>This isn't particularly hard...but I like it.</p>
<p>A and B are both positive integers. (a^1/2 x b^1/3)^6=432. What is ab?</p>
<p>Answer:
Factor 432 and you should get 3^3 x 2^4, and that 2^4 is equal to 4^2 therefore the answer is 12</p>
<p>Thanks for posting that one s snack. If I saw something like that I would probably be stumped. (And I have 36 Math ACT, 800 Math IIC!)</p>
<p>2x - 5y = 8
4x + ky = 17</p>
<p>For which of the following values of k will the system of equations above have no solution?</p>
<p>(A) -10
(B) -5
(C) 0
(D) 5
(E) 10</p>
<p>Is it (A)?
I do not know the answer; I tried to find it on CB's website, but my search turned out to be useless. (This is from last year's PSAT Score Report.)</p>
<p>well. the bottom equation is just the top equation multiplied by 2.</p>
<p>Accordingly, 4x - 10y must equal 16.</p>
<p>But if 4x - 10y = 17, there's no value for x or y that equals both.</p>
<p>OK. Just a math challenge here.</p>
<p>The total sum of the squares of each side of a right triangle is 200.
What is the length of the hypotenuse?</p>
<p>Yeah I think it would have to be A. Because if you multiply equation one by 2 you get 4x-10y=16. 4x+ky=17. So if k was -10 it obviously wouldn't work.</p>
<p>(a^2+b^2)+c^2=200</p>
<p>a^2+b^2=c^2</p>
<p>c^2+c^2=200
c^2=100
c=10</p>
<p>I got the same thing dsmo...
This is a good thread for practice...keep this up guys.</p>
<p>OK, I know that these questions are easy for you guys, but I'm doing some practice problems and I can't figure them out.</p>
<p>This is number 13 in section 3 of practice 2 of the blue book:
[quote]
CityTemp (°)
A50
B33
C27
Dt
E68
F44
G40</p>
<p>The table above shows the noon temperatures for seven cities designated A through G. If the median noon temperature of these cities is 40°F, then the noon temperature for City D could be any of the following EXCEPT</p>
<p>(A) 29°F
(B) 35°F
(C) 39°F
(D) 40°F
(E) 42°F
[/quote]
Are they saying that, when the value the median temperature of all seven cities is 40? I am confused because, if there are seven cities, then the median temperature would be the 4th city; but it says that all work except one. I must be misreading the problem.</p>
<p>and this problem is from a barron's practice book:
[quote]
A jar contains four blues marbles and two green marbles. Without looking, two marbles are drawn from the jar. What is the probability that two marbles with the same color will be selected?
[/quote]
It's a grid-in. I listed out the possibilities:</p>
<p>Blue first: B,B; B,B; B,B; B, G; B,G
Green first: G, G; G,B; G,B; G,B; G,B</p>
<p>There are two possibilities, and four choose the same color. I thought it was 4/10 or 2/5, but apparently it's 7/15. The Barron's book has an explanation but I didn't really understand it and I'd appreciate if anyone could tell more where I went wrong.</p>
<p>I'll have more :)</p>
<p>The first one is E, because median=40, so three must be greater than or equalt to 40 and three must be less than or equal to 40, but there are only 2 less than, so it has to be less than or equal to 40, and 42 is the only one that doesn't work.</p>
<p>The second one is very simple as well. First of all, there are 2 ways to get 2 of the same colors. 2 blues, and 2 greens. So the probability of getting either one of those 2 will be the probability of getting 2 blue + prob. of getting 2 green.
Prob of getting 2 blue:
1st draw: 4/6 chance
2nd draw: 3/5 chance
1dx2d= 12/30= 6/15</p>
<p>Prob of getting 2 green:
1st draw: 2/6 chance
2nd draw: 1/5 chance
d1xd2=2/30=1/15</p>
<p>Blue+Green= 7/15</p>
<p>Its not very hard but here goes:</p>
<p>If 4(x+y) (x-y) = 40 and x-y=20, what is the value of x+y?</p>
<p>The first one is E, 42, because whenever you have a median oriented problem, the first thing you do is take the numbers and put them in increasing numbers. So you have, 27, 33, 40, 44, 50, 68. Now if you pick any number between 40 and 44, that number will be the median because it will be the 4th number. However, the median is suppose to be 40, so the number can't be between 40 and 44, so the answer is 42 (E). The second one has to do with independent multiplying and stuff I learned in statistics last year, I can't remember and I'm too lazy to think it out right now, sorry.</p>
<p>(x+y)(x-y)=10
(x+y)(20)=10
x=y=1/2</p>
<p>First one is 42 because it is above the median (that would leave 4 above 40 and shift medium upward.</p>
<p>Second is 7/15. Do blues first - 4/6 * 3/5 = 12/30 and then green 2/6*1/5. Add them up and you get 7/15 when reduced to lowest terms.</p>
<p>Anther one 'medium' question. (I seem to get all the 'hard' ones right)</p>
<p>A school ordered $600 worth of lightbulbs. Some of the lightbulbs cost $1 each and the others cost $2. If twice as many $1 bulbs as $2 bulbs are ordered, how many were ordered altogether?</p>
<p>sort it out
x=@ $1/bulb
y=@ $2/bulb=.5x</p>
<p>P=1x+2y=x+2(.5x)=2x therefore x=300</p>
<p>300 at $1/per and 150 at $2/per so 450 total</p>
<p>Thanks for the responses. When exactly do you add the probabilities? And what does mean, mathematically, when do "either/or" probabilities occur?</p>
<p>Two more problems that are confusing me:
[quote]
The price of ground coffee beans is d dollars for 8 ounces and each ounce makes c cups of brewed coffee. In terms of c and d, what is the dollar cost of the ground coffee beans required to make 1 cup of brewed coffee?
[/quote]
I know it's probably really easy, but I don't know how to set this one up.</p>
<p>and:</p>
<p>
[quote]
A store charges $28 for a certain type of sweater. This price 40 percent more than the amount it costs the store to buy one of these sweaters. At an end-of-season sale, store employees can purchase any remaining sweaters at 30 percent off the store's cost. How much would it cost an employee to purchase a sweater of this type at this sale?
[/quote]
I'm probably just not thinking clearly here. I did 28/.4 as the store cost and then multiplied it by .7 to get the employee cost. Help is appreciated :)</p>
<p>why does it have to be math lol ...?</p>
<p>lol someone post up grammar questions...</p>
<p>the coffee one i have no idea how, but I think ( I'm not taht good at this but bare with me) its d/8c....I think.....
I figured if 8 ounces is d dollars then 1 ounces is d/8..... and if one ounce makes c cups then 1 cup is (d/8)/(c) so then the price per cup would be d/8c....its probably wrong, so feel free to make fun of my attempt at math lol</p>
<p>and for the employee one I did: x= amount it cost the store to buy it
so what it costs costumers is 28=x+0.4x right? so find x= 20, and so the emplooyee can purchase it at x-0.3x , so he can purchase it at 14.... I'm a bit more confident in this one, but it might be wrong aswell</p>