<p>So I have another Q ( what a shocker!!!)</p>
<p>How many numbers greater than 400 but less than but less than 10.000 can be formed using the digits 0,1, 2,3,4 and 5 if no digit may be used more than once in any number? Btw the answer is 340.</p>
<p>let me think for a while. btw, i scored 800 on my first sat practice test and so on. kk</p>
<p>let's divide the solution for this prob into 2 parts.
the number can be 3 digit number. in this case, the number should start with 4 or 5, since it's told be over 400.
4ab (imagine it as 3 digit number starting with 4). then, 5 other choices left for a and 4 for b. in total, it's 5<em>4=20;
5cd. we should do the same here. 5 choices for c, and 4 choices left for d. again it's totally 20.
if the number were 4 digit, it would look like abcd. and 5 choices for a (first digit can't be 0 - so it's 5), 5 again for b (including 0), 4 for c, and 3 for d. totally it will be 5</em>5<em>4</em>3=300.
and it's 300+40=340 in grand total. isn't it the number you wanted to see, huh??</p>
<p>Tsenguun: Yeah, but how is Humna going to learn anything if we keep telling her the answer? I think it's best if Humna tries to figure it out on her own. </p>
<p>Humna: Would it be better if we gave you hints to get you started and then have you try to answer on your own, rather than just tell you how to do the whole problem? I'm concerned that you won't really learn how to do the problems. Did you go over the sparknotes website on this thread?</p>
<p>dchow, the answer to your miles question from ~4 pages back is 5, right?</p>
<p>Humna, where do you get your questions from?</p>
<p>brosfam: For rate problems, you may want to use a chart to organize your data. Later on, when you get more practice, you will be so used to doing these problems that you don't even need a chart anymore.</p>
<p>speed x time = distance
mph hours miles</p>
<ol>
<li>Biking: Speed: 5 Time = m/5 Distance = m </li>
<li>Bussing: Speed: 20 Time = m/20 Distance = m
TOTAL: Time = 1</li>
</ol>
<p>m/5 + m/20 = 1.</p>
<p>Solving for m we get m = 4.</p>
<p>I got 4 as the answer.</p>
<p>dchow08: Okay, I'll follow you, man. But I did improve my math just reading a book full of problem solutions. Sometimes it helps a lot. Though, in this case, it's best that Humna should try to solve them on her own.</p>
<p>
[quote]
</p>
<p>EXAMPLE 1
If the probability that person A will be alive in 20 years is 0.7 and the probability that person B will be alive in 20 years is 0.5, what is the probability that they will both be alive in 20 years?</p>
<p>Answer
These are independent events, so</p>
<p>P(E1 and E2) = P(E1) </p>
<p>dchow08: I don't know much about these probabilities as above. Can you help us review the concept?</p>
<p>My guess would be one person might have a disease that could be passed on to another person? That's the best I can think of.</p>
<p>Here's the basic definitions of those probability terms
Dependent events: When one event has a direct effect on another event, such as when you pick up cards from a standard deck to form a five card hand. The probability of getting a heart changes each time because the deck gets smaller each time, and plus you might get a heart as well. Picking two balls from a jar of different colored balls without replacement is also dependent for the same reasons.
Independent events: Two events such that one event has no effect on the other. If you did the example with the jar above but put the ball you drew back in the jar, your first and second draw will be independent because what you did the first time will have no influence on what you will do the second time. The probability for two independent events happening is just the product of the probabilities of the two events happening</p>
<p>Thanks Gator. I think you are probably right about the question I had.</p>
<p>Also, do you guys prefer plugging answer choices in and using your calculator over thinking deeply about how to solve a problem? </p>
<p>For example, I know many problems that can be solved in a variety of ways. The explanations have presented me with some ways of solving them fast, but they are hard to come up with. Given the time restraints for each section, should you try to think up those shortcuts or should you just guess and check the answers until you come up with the right one?</p>
<p>What if you try to think up the shortcut in vain? I just don't know which way to go because if you guess and check, you may make a mistake there and end up eliminating all of them... So, what do you guys do to get an 800 in the Math section?</p>
<p>p.488</p>
<h1>5...Is a graph...someone with the blue book please help...Graph of function h. Which number is closest to h(5)</h1>
<p>a.1
b.2
c.3
d.4
e.5</p>
<p>answer is c. 3...why?</p>
<h1>6 is picture of 3 line segments joined to make a Y shape...3 angles are formed labeled 4x, 2x, 3x? What is the value of x?</h1>
<p>blue book said since the angles must all add up to 360...you do 4x+2x+3x=360
9x=360....x=40</p>
<p>MY question is how do know the angles add up to 360...is there a clue/ rule or theorem?
p.490 #12</p>
<p>Someone w/ blue book please help....it is a picture of a rectangle...
ABCD rectangle with BC=4 and AB=6. Points p,q and R are different points on a line parallel to line AD. Points P and Q are symmetric to line AB and QR is symmetric with CD.</p>
<p>What is the length of line PR?</p>
<p>a.6
b.8
c.10
d.12
e.20</p>
<p>answer is 8...please explain</p>
<h1>15</h1>
<p>I dont have the blue book with me now but i know for #6 the 3 line segments essentially form a circle(more like an oval)</p>
<p>but in the book it looks like a y....how are you supposed to know it is a oval</p>
<p>ah you're a genius trois :D</p>
<p>Thns tsengunn for answering the Q. </p>
<p>Dchow:I only post problems here which I have tried and dun get, stuff which I havnt ever cum across before, concepts I'm not acquainted with. I really wanna get a 800 on the maths section of my upcoming SAT...which is probably impossible. Im gonna try harder to do my own Qs from now on.
Ur rite, if I depend on others i'll never learn myself. N yes im checking out that link u posted. Thnx :)</p>
<p>Amu: I get my Qs from various online sources and some from books.</p>
<p>well i just visualized by myself.</p>
<p>can someone please help answer my questions?</p>
<h1>6 How do you know that the Y is 360 degrees?</h1>
<p>Think of it like this, draw for yourself that arc thing that is usually seen with every angle drawing for each angle that you see. It should come up to be a circle if you drew them all.</p>
<h1>12 I don't have the blue book but your words are clear enough for me to follow. P and Q are between line AB, and both points are equidistant to line AB. Let's call the distance between line AB and either point P or Q "x". The same follows for Q, R, and CD. Let's call the distance between line CD and either point Q or R "y". You said the 3 points are parallel to line AD, which has a length of 4 due to it being a rectangle.</h1>
<p>It's hard to explain without pictures, but if you drew everything correctly and labeled everything as I said, you will find that
2x + 2y = the length of PR
and also,
x + y = the length of AD = 4
therefore,
since x + y = 4, 2(x + y)=8, which is the length of PR</p>
<p>I think I found an easier explanation for the circle thing.
Whenever you have a bunch of lines that connect at a single point which is at the center, they will have angles that add up to 360 degrees.</p>