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A rectangular lot 120 feet long by 80 feet wide is to be
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29 Feb 2012, 15:24
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A rectangular lot 120 feet long by 80 feet wide is to be partitioned into 10 retangular gardens. If each of the gardens will have the same dimensions, how many feet of partitioning will be needed to seperate the garden? (1) one of the demensions of each garden is to be 40 feet. (2) one of the dimensions of each garden is to be 24 feet.
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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29 Feb 2012, 17:48
Hi, there. I'm happy to help with this. The prompt: A rectangular lot 120 feet long by 80 feet wide is to be partitioned into 10 rectangular gardens. If each of the gardens will have the same dimensions, how many feet of partitioning will be needed to separate the garden?That part highlighted is HUGE hint in the prompt. The total area is 120 x 80 = 9600, so the gardens must each have an area of 960. If we know one side of a rectangle with area 960, we can find the other side. Statement #1: one of the dimensions of each garden is to be 40 feet.960/40 = 96/4 = 24 (notice, this means 24*40 = 960 ... good to know!) So we have 40x24 rectangles. The length of 24 doesn't go evenly into 80, so we must use five of the 24 lengths to fill out the 120 dimension. That leaves two 40 lengths in the 80 direction, for a two x five configuration of the gardens. This would allow us to figure out the extra perimeter. Statement #1, by itself, is sufficient. Statement #2: one of the dimensions of each garden is to be 24 feet.Because we found that 24*40 = 960, we know 960/24 = 40. This leads to the same situation we had in #1, so statement #2, by itself, is sufficient. Does that make sense? Please let me know if you have any further questions. Mike
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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03 Apr 2012, 03:44
mikemcgarry wrote: Hi, there. I'm happy to help with this. The prompt: A rectangular lot 120 feet long by 80 feet wide is to be partitioned into 10 rectangular gardens. If each of the gardens will have the same dimensions, how many feet of partitioning will be needed to separate the garden?That part highlighted is HUGE hint in the prompt. The total area is 120 x 80 = 9600, so the gardens must each have an area of 960. If we know one side of a rectangle with area 960, we can find the other side. Statement #1: one of the dimensions of each garden is to be 40 feet.960/40 = 96/4 = 24 (notice, this means 24*40 = 960 ... good to know!) So we have 40x24 rectangles. The length of 24 doesn't go evenly into 80, so we must use five of the 24 lengths to fill out the 120 dimension. That leaves two 40 lengths in the 80 direction, for a two x five configuration of the gardens. This would allow us to figure out the extra perimeter. Statement #1, by itself, is sufficient. Statement #2: one of the dimensions of each garden is to be 24 feet.Because we found that 24*40 = 960, we know 960/24 = 40. This leads to the same situation we had in #1, so statement #2, by itself, is sufficient. Does that make sense? Please let me know if you have any further questions. Mike Can you pls show in a diagram how u use 80.according to my thought process width 80 ill remain unaffected.and we ill divide length 120 in 10 gardens
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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03 Apr 2012, 06:19
mikemcgarry wrote: Hi, there. I'm happy to help with this. The prompt: A rectangular lot 120 feet long by 80 feet wide is to be partitioned into 10 rectangular gardens. If each of the gardens will have the same dimensions, how many feet of partitioning will be needed to separate the garden?That part highlighted is HUGE hint in the prompt. The total area is 120 x 80 = 9600, so the gardens must each have an area of 960. If we know one side of a rectangle with area 960, we can find the other side. Statement #1: one of the dimensions of each garden is to be 40 feet.960/40 = 96/4 = 24 (notice, this means 24*40 = 960 ... good to know!) So we have 40x24 rectangles. The length of 24 doesn't go evenly into 80, so we must use five of the 24 lengths to fill out the 120 dimension. That leaves two 40 lengths in the 80 direction, for a two x five configuration of the gardens. This would allow us to figure out the extra perimeter. Statement #1, by itself, is sufficient. Statement #2: one of the dimensions of each garden is to be 24 feet.Because we found that 24*40 = 960, we know 960/24 = 40. This leads to the same situation we had in #1, so statement #2, by itself, is sufficient. Does that make sense? Please let me know if you have any further questions. Mike MIke, the solution looks simpler after the explanation is read...so is it that whenever somebody says the a plot is divided equally in n divisions, we can calcualte teh area and then divide by it...is it always the method to do this type of problems?
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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03 Apr 2012, 14:34
GMATD11 wrote: Can you pls show in a diagram how u use 80.according to my thought process width 80 ill remain unaffected.and we ill divide length 120 in 10 gardens What you are doing is figuring out how to answer the prompt question in your own way, ignoring the two statements. In GMAT DS, that is a trap. Any answers you figure out to the prompt that are not allowed by the statements are not relevant to solving the question. There are a number of ways to divide a 120 x 80 plot into 10 equal rectangles. As you said, we could have ten plots that were 80 x 12. We could also have ten plots that were 8 x 120. Both of those are possible, but neither is consistent with either statement, so for the purposes of solving this DS, both of those are 100% irrelevant. Your job on DS is not to read the question and think for yourself how to solve the question. Your job, quite specifically, is to determine whether the statements, individually or together, will help you answer the question. Remember: answering a DS question is very very different from solving a math problem. See this blog: http://magoosh.com/gmat/2012/introducti ... fficiency/Does that make sense? Let me know if you have any questions. Mike
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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03 Apr 2012, 14:51
harshavmrg wrote: Mike, the solution looks simpler after the explanation is read...so is it that whenever somebody says the a plot is divided equally in n divisions, we can calculate the area and then divide by it...is it always the method to do this type of problems? Dividing the area is one good strategy to have. Whenever you are dealing with larger numbers, thinking about those numbers in terms of their factors can be a helpful approach. We can't say, though, that this is the approach to use "always." Among other things  every question about area is going to be different. The GMAC excels at creating new questions that do not resemble anything previously asked. You need to master the math content and have a flexible approach in terms of strategy. Even if the question is about dividing up a plot, a real curveball can occur if it's possible to lay the rectangles going in two different ways. Attachment:
garden divided into 16 equal rectangles.JPG [ 25.35 KiB  Viewed 5952 times ]
In this diagram, which divides the 80 x 120 plot into 16 equal rectangles, not all going the same way. I checked for that in the above DS question, and saw that it wasn't possible, but I didn't go into that level of detail in my explanation. Technically, you should be on the lookout for alternate configurations like that, which means you can't simply divide. Nevertheless, questions in which those alternate geometric configurations of rectangles filling a plot are possible do strike me as a bit harder than what the GMAT would ask. I realize that this is probably a more complicated answer than that for which you were hoping. Does all this make sense? Please let me know if you have any further questions. Mike
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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05 Apr 2012, 19:50
stumped by the question. Went over from my head. Thanks mike for explanation. +1
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Re: A rectangular lot 120 feet long by 80 feet wide is to be
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