blover Posted October 7, 2008 Share Posted October 7, 2008 http://i37.tinypic.com/6oq0c0.jpg please suggest shortest efficient technique like the technique shown below the point 47 http://i37.tinypic.com/2lu97hc.jpg for solving ratio question. Quote Link to comment Share on other sites More sharing options...
e.cartman Posted October 7, 2008 Share Posted October 7, 2008 I donno short-cut but this is my method. I get B. 15 min is 1/4 hr 20 min 1/3 hr 1400 rooms * 1/4 = 350 hrs by 1 person 420 * 1/3 = 140 hrs by 1 person Total 490 hrs by 1 person Or 490/7 = 70 men for 7 hrs. Quote Link to comment Share on other sites More sharing options...
blover Posted October 7, 2008 Author Share Posted October 7, 2008 20 minutes is 1/3 of hr or 2/3 ? Quote Link to comment Share on other sites More sharing options...
e.cartman Posted October 7, 2008 Share Posted October 7, 2008 Oops! My mistake. I corrected it in situ. To think the authors have an answer option to catch that. :devil: Quote Link to comment Share on other sites More sharing options...
coolaman Posted October 7, 2008 Share Posted October 7, 2008 I got B. 70 persons. Quote Link to comment Share on other sites More sharing options...
blover Posted October 7, 2008 Author Share Posted October 7, 2008 how suggest technique? Quote Link to comment Share on other sites More sharing options...
bose Posted October 10, 2008 Share Posted October 10, 2008 1 room by 1 person in 15mins nin 7 hrs i.e. 420 mins one person can do 28 rooms so to do 1400 rooms we need 1400/28=50 people similary we get 20 people for 420 large rooms ands 70 Quote Link to comment Share on other sites More sharing options...
genius_in_the_gene Posted October 10, 2008 Share Posted October 10, 2008 Imo B. Quote Link to comment Share on other sites More sharing options...
trigeminal Posted October 11, 2008 Share Posted October 11, 2008 B Total time required- (1400x15)+(420x20)=29400min Total time available- 7x60 = 420min No of persons required=29400/420 = 70 persons (easy to calculate after omitting zeroes) Quote Link to comment Share on other sites More sharing options...
mail2jkd Posted October 11, 2008 Share Posted October 11, 2008 20 minutes is 1/3 of hr or 2/3 ? 20/60 = 1/3 Ans B - 70hrs Quote Link to comment Share on other sites More sharing options...
blover Posted October 12, 2008 Author Share Posted October 12, 2008 i figured out efficient way to do this 1400*15 + 420 *20 = 420 X X= 50 +20 => 70 ans Quote Link to comment Share on other sites More sharing options...
theRealGMATstrategies Posted October 12, 2008 Share Posted October 12, 2008 allright, this problem is fairly simple. However, as always, the GMAT tricksters confuse the wording to delay you finding the right solution. So, the best way with problems of this kind is always figure out how much a person does in one hour. In this case, you can easily establish that one person does 4 single rooms in one hour and 3 double rooms in one hour. Next, in seven hours one person can do 28 single rooms and 21 double rooms. The last step is to set up a ratio 1p/28=x/1400 and 1p/21=y/420. Add the values for x and y to get the total number of people. There are ways to de-confuse this problem through simple drawing, but unfortunately I can not show that --- although if you are interested ---- I could show - just email me. Also, remember, that there are different ways to solve this problem. However, also remember, that the GMAT tricksters rely on you to use algebra because they know that under time pressure if you use algebra, you are likely to make a mistake, so whenever you can try to avoid algebra without sacrificing time. I solved this problem in 2 minutes 19 seconds. This is a bit too long, as you need to keep your timing at 2 minutes per problem. If you are interested in talking about timing strategies, etc, email me, and we will talk.... Quote Link to comment Share on other sites More sharing options...
theRealGMATstrategies Posted October 12, 2008 Share Posted October 12, 2008 One more thing. I think this problem is a wonderful example of what I call the "Break-Layer" GMAT method. What this means is that GMAT tests relatively easy math concepts. In this particular problem, the concept being tested is the ratio. However, if you notice the test makes you use three different ratios in order to solve this problem. So, by piling up the concept of ratio and feeding you a confusing word content, the GMAT tricksters are making you use valuable time. Quote Link to comment Share on other sites More sharing options...
rkwagle Posted October 12, 2008 Share Posted October 12, 2008 Imo B Quote Link to comment Share on other sites More sharing options...
blover Posted October 14, 2008 Author Share Posted October 14, 2008 earlier i use that approach 15minutes -- 1 room 420 minutes --- X room x=28 rooms 28 rooms --1 man 1400 rooms --x man x=50men 20 min --1 room 420min --x rooms x=21rooms 21rooms---1man 420rooms--- -xmen x=20men so 50men plus 20 men =70men Quote Link to comment Share on other sites More sharing options...
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