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04-14-2011, 10:51 PM   #61
Junior Member

Join Date: Apr 2011
Posts: 174
Quote:
 Where A is not equal to 1, (A^7-A^6)/(A-1)=? A)a/(a-1) B)1/(a-1) C)A^6-A^5 D) A^5 E)A^6 The book says E, and I guessed A. How do you do this one?
Get a Ti-89!
 06-18-2011, 10:57 PM #62 Junior Member   Join Date: Oct 2010 Posts: 123 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/?) Reply
 06-19-2011, 07:50 PM #63 Junior Member   Join Date: May 2010 Posts: 242 the total is 10 because is 5 C 3. so you get 10 since there are a total of five peopel for 3 spots. Reply
06-22-2011, 08:17 PM   #64
Junior Member

Join Date: Dec 2010
Posts: 176
Quote:
 Where A is not equal to 1, (A^7-A^6)/(A-1)=? A)a/(a-1) B)1/(a-1) C)A^6-A^5 D) A^5 E)A^6 The book says E, and I guessed A. How do you do this one?
factor out A^6 from numerator: A^6(A-1)/(A-1)

then divide out (A-1)
 06-22-2011, 09:01 PM #65 Junior Member   Join Date: Oct 2010 Posts: 123 What is the least interger greater than 999 that is divisible by 6, 8, 9? 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) Reply
 06-24-2011, 06:18 PM #66 Junior Member   Join Date: Oct 2010 Posts: 123 bump. anyone? Reply
 06-24-2011, 06:28 PM #67 Junior Member   Join Date: Jun 2010 Posts: 208 Id just use trial/error. It works nearly 100% of the time and I don't feel like memorizing random facts and theorems Reply
 06-25-2011, 01:51 AM #68 Junior Member   Join Date: Jun 2011 Posts: 278 Use prime factorization. 6 is 2*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)*(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. Reply
 07-03-2011, 08:29 PM #69 Junior Member   Join Date: Jan 2011 Posts: 25 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 19. How many of the orchards grew no apples, pears, or plums? a) 0 b) 80 c) 165 d) 235 e) 320 Reply
 07-03-2011, 09:17 PM #70 Junior Member   Join Date: Oct 2010 Posts: 123 18. the answer is a 19. I think the answer should be 50 but I dont see it as a choice? 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. Reply
 07-03-2011, 09:25 PM #71 Junior Member   Join Date: May 2010 Posts: 242 whre did u get these problems from? is the first one D) 180 and the last one b) 80 . Reply
 07-03-2011, 09:31 PM #72 Junior Member   Join Date: May 2010 Posts: 242 whre did u get these problems from? is the first one D) 180 and the last one b) 80 . Reply
 07-03-2011, 09:58 PM #73 Junior Member   Join Date: May 2010 Posts: 242 nvr mind i think ezrahusney is right about the last one. i think it is 50 also. Reply
 07-03-2011, 10:35 PM #74 Junior Member   Join Date: May 2010 Posts: 242 the first one should be 150 b/c u have to do (250-70-30-10) + (95-45-30) apples + plums Reply
 07-03-2011, 10:38 PM #75 Junior Member   Join Date: Jun 2011 Posts: 44 @ 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.? Reply

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