<p>I hate permutations, probablilty and all. I never learned it.</p>
<p>Here's a question:</p>
<p>A basket contains 10 apples, of which 5 are rotten. What is the probabilty that a person who buys 4 apples will get none that are rotten?</p>
<p>a) 1/2
b) 2/5
c) 2/25
d) 1/4032
e) 1/42</p>
<p>Can some give me some brief explanation of permutations, combinations and the binomal theorem and how to use them? Thanks</p>
<p>Oh and are these questions common on the real thing?</p>
<p>I'm pretty weak with probabilities too, but I think it's e.</p>
<p>The important thing to remember here is that probability is multiplicative. So if you have a 1/2 chance of one thing happening, and a 1/3 chance of another thing happening, there's a 1/6 chance that both things will happen. So you have to account for all the possible chances.</p>
<p>You have a 5/10 chance, or 1/2, that you'll get a fresh apple the first time.
Since you chose an apple, there are now 9 apples, 5 of which are rotten. So there is a 4/9 chance of getting a fresh one. And then 3/8, and 2/7. If you multiple 1/2, 4/9, 3/8, and 2/7, you get 1/42. Hopefully I got that right :)</p>
<p>I think theres only one question on permutations/combinations</p>
<p>Yes syn that's how the book explains it. Thanks</p>
<p>I still am confused on the basic idea of probs, permutations and the binomial theorem.</p>
<p>10/15.9/14.8/13.7/12</p>
<p>Rusen Meylani</p>
<p>There's a simpler way to do this problem. Since they're are 10 apples and 5 are rotten, 5 are not rotten. Therefore, you are choosing 4 out the 5 not rotton apples. This can be shown as C (5,4). The total number of possibilities is represented by C (10,4) because there are a total of ten apples to choose from. C (5,4)/ C (10,4) simplifies to 1/42.</p>
<p>I have another question. I should have studied, but I didn't. The last time I touched math of any sort was during the AP test--which, as you guys know, was about exactly a month ago.</p>
<p>I'm totally failing.</p>
<p>How do you guys find the distance between (-3, 6, 7) and (2, -1, 4)? I can't this remember at all, and suddenly it seems incredibly difficult.</p>
<p>radical((x2-x1)^2+(y2-y1)^2+(z2-z1)^2)</p>
<p>Islander is right. One way to think of 3-d distances (or the diagonal of a rectangular solid) is the "pythagorean theorem in 3 dimensions" approach.</p>
<p>In 2 dimensions, c^2 = a^2 + b^2.</p>
<p>In 3 dimensions, d^2 = a^2 + b^2 + c^2.</p>
<p>Muchos gracias. </p>
<p>Another question. For some real number t, the first three terms of an arithmetic sequence are 2t, 5t-1, and 6t+2. What is the numerical value of the fourth term?</p>
<p>I don't even know what they're talking about.
I'm a disgrace at math.</p>
<p>An arithmetic sequence is one in which you simply add a number to one term to get the next term. For example: 3, 5, 7, 9, 11... where you add two to each term.</p>
<p>So in this case, say you add x to each term. Therefore:</p>
<p>The first term + x = the second term.
2t + x = 5t - 1. Solve for x ==> x = 3t - 1</p>
<p>Do the same for the second and third terms:</p>
<p>5t - 1 + x = 6t + 2 ==> x = t + 3</p>
<p>Substitute:</p>
<p>3t - 1 = t + 3 and solve for t ==> t = 2</p>
<p>So, the first term is 4, the second is 9, the third is 14....we're just adding 5 here, so the fourth term is 14+5 or 19.</p>
<p>i believe its 19 --- petes right on the money</p>
<p>Thanks! Do you guys know where I can review (for free, online, and as quickly as possible) for math, specifically, the terms? I think I have lit and world history down, but this math is killing me.</p>
<p>I know it's last minute, but you might find it more efficient to get a Math IIc prep book...the books will target the specific terms you need to know better than any website I'm aware of. It's possible your library or college counselor's office will have a copy...</p>
<p>BTW, a geometric sequence involves multiplying each term by a constant to get the next term...</p>
<p>maybe a quicker way would be, if its terms a,b,c. A+C/2=b, it works for arithmetic dunno bou geometric though</p>
<p>It is 19. I solved it a different way though. The difference between the first two terms is 3t-1 and the difference between the second and third terms is t+3. So 3t-1=t+3. Solve to get t=2. Plug in 2 for t to get the fourth term equal to 19.</p>
<p>anyone wanna try this one?</p>
<p>all of these logs are in base 3</p>
<p>DOES ANYONE KNOW HOW TO DO DIFFERENT LOG BASES ON A TI-89???</p>
<p>log3(m) = 1.5 - log3(n)</p>
<p>What is mn?</p>
<p>log3(m)+log3(n)=1.5
log3 (mn)=1.5 (combine using log rule)
3^1.5=mn</p>
<p>you can do different logs by just using the change of base theorem
log2(10)=log 10/log2</p>
<p>What math are you currently in?</p>
<p>I just finished up Ap Ab calc, doing BC next year. Wait, so how do you do logs w/ different bases on a TI-89?</p>