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<p>Get a Ti-89!</p>

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<p>Heres a probability question.
There are 3 Republicans and 2 Democrats on a Senate committee. If a 3 person subcomittee is to be formed from this committee, what is the probability of selecting 2 Republicans and 1 Democrat?
I know that no. of ways to select 2 Rep. is 3, and that no. of ways to select 1 Dem. is 2 for 6 (3 x 2) possible ways. But how do you determine the total number of ways?(6/?)</p>

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<p>the total is 10 because is 5 C 3. so you get 10 since there are a total of five peopel for 3 spots.</p>

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<p>factor out A^6 from numerator: A^6(A-1)/(A-1)</p>

<p>then divide out (A-1)</p>

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<p>What is the least interger greater than 999 that is divisible by 6, 8, 9?</p>

<p>I was able to do this question fairly quickly by trial and error but was wandering if there is perhaps a mathematical and more direct approach. (maybe prime factorization)</p>

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<p>bump. anyone?</p>

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<p>Id just use trial/error. It works nearly 100% of the time and I don’t feel like memorizing random facts and theorems</p>

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<p>Use prime factorization. 6 is 2<em>3, 8 is 2^3, and 9 is 3^2. The find the LCM, just choose the highest power of each factor. This gives you (2^3)</em>(3^2) = 8*9 = 72. Thus the number must be a multiple of 72. It is simple to see that the first multiple of 72 greater than 999 is 1008.</p>

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<p>difficult set question: a study of 400 fruit orchards showed that 250 of the orchards grew apples, 140 grew pears, 95 grew plums, 70 grew only apples and pears, 30 grew only apples and plums, 45 grew only pears and plums, and 10 grew all three.
18. how many of the orchards grew only apples or plums?
a) 30
b) 130
c) 150
d) 180
e) 345</p>

<ol>
<li>How many of the orchards grew no apples, pears, or plums?
a) 0
b) 80
c) 165
d) 235
e) 320</li>
</ol>

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<ol>
<li>the answer is a</li>
<li>I think the answer should be 50 but I dont see it as a choice? </li>
</ol>

<p>The easiest way to solve this is to make a venn diagram with three circles. Start with the last piece of information and work your way back while filling in your chart. I’m not sure why I’m not getting an answer choice for q 19. Maybe there is a mistake.</p>

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<p>whre did u get these problems from? is the first one D) 180 and the last one b) 80 .</p>

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<p>whre did u get these problems from? is the first one D) 180 and the last one b) 80 .</p>

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<p>nvr mind i think ezrahusney is right about the last one. i think it is 50 also.</p>

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<p>the first one should be 150 b/c u have to do (250-70-30-10) + (95-45-30)
apples + plums</p>

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<p>@ Arachnotron
this is related to GRE’s question about rate and time. I figured out the rates but can you explain why you did this : (27sec/90ft)(100ft) = 30 seconds.?</p>

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<p>guys, the answers are 18. C (150) so altamash got it correct, 19. B (80) i dont understand why though</p>

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<p>I’m sorry, I misread the question. q 18 is indeed 150.
19. the answer is b) 80. @altamash why did you switch answers</p>

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<p>oops I was writing while you posted it.
Here is my explanation: first make 3 overlapping circles labeled apples, pears, and plums
fill out the venn diagram as follows

  1. the place where the 3 circles intersect will be 10
  2. the place where only apples and plums intersect will be 30
  3. the place where only pears and plums intersect will be 45
  4. the place where only apples and pears intersect will be 70
  5. remaining apples will be 250-30-10-70=140
  6. remaining pears will be 140-70-10-45=15
  7. remaining plums will be 95-30-10-45=10</p>

<ol>
<li> only apples or only plums is 140+10=150</li>
<li>to see how many are none use 400-140-30-70-10-15-45-10=80</li>
</ol>

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<p>thank you so much, that was a really great explanation</p>

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<p>In the BB, there is this example question concerning combinations:
There are 12 students in the school theater class. Two students will be responsible for finding the props needed for the skit the class is performing. How many different pairs of students can be chosen to find the props?</p>

<ul>
<li>To get the answer, you first multiply 12 by 11 to get the number of ways of choosing a pair of students, and then you divide by 2 because each pair of students can be chosen in two different ways. The answer is 66.</li>
</ul>

<p>I do not understand why we have to divide by 2 because each pair of students can be chosen in two different ways. I thought in combinations, the order doesn’t matter, so we shouldn’t have to worry about this. And why are we dividing? I am confused. :(</p>