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jeff1949

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Apr 4, 2011
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The length of a rectangle is 3m less than the width. The area of the rectangle is 7m2
Find an estimate for the width of the triangle.
 
See, you didn't do the "show your best efforts" part.

Note: "Estimate" problems are intended to be a little vague. This is also a good method to begin any problem. On the GCSE, you don't always have time to be particularly formal. You must improve your skills at estimating.

Learn to dump information:

Rectangle.
4 right angles
2 pair of parallel sides
Width (W) and Length (L)
Perimiter 2W+2L
Area W*L -- Aha!! There is one we can use on this problem.
 
Sorry I did say i was a beginner. What did you mean by "give it your best efforts"

I can understand the parts about 4x90 angles in a rectangle and two opposite sets of angles but how do measure the area of a rectangle which is 7m squared. I know you don't give out full tutorials but i just don't understand the question?
 
Ted,

The question should read rectangle not triangle. I can see if you add the two widths, 2m each and the two lengths 1.5m then added together it would make 7m squared. eg (2+2+1.5+1.5 = 7, but how do i make it 3 metres less?
 
Let's start all over.

First if you read the Read Before Posting you will see that it is a great help if you tell us not just the problem but what you have already done to solve it. That way we can figure out where you are stuck and not waste your time and ours.

The length of a rectangle is 3m less than the width. The area of the rectangle is 7m2
Find an estimate for the width of the
rectangle.

A good first step is to write down concisely but carefully some definitions. Stick a letter in for unknowns.

Width of rectangle = W.
Length of rectangle = L.
Area of rectangle = A = 7m[sup:acf46vov]2[/sup:acf46vov].

Now see if you can relate those definitions in some logical way.

What is the area of a rectangle? This problem assumes that you know this fact.

A = W * L, right?
So, 7 = W * L. One equation in two unknowns. Not good. Have we used all the information? No. There is a relation between W and L.

What is it?
 
jeff1949 said:
Sorry I did say i was a beginner. What did you mean by "give it your best efforts"

I can understand the parts about 4x90 angles in a rectangle and two opposite sets of angles but how do measure the area of a rectangle which is 7m squared. I know you don't give out full tutorials but i just don't understand the question?

Your kind of missing the point. I was not writing a list for you to memorize. I was suggesting that as you approach such a problem, you dump on the page all that you know. Just get it out there. If you don't know some of the stuff I dumped for my example, this is not the point. Get what you know out on the paper or at least let it pas through your mind.

In this case, if the relationship between length and width is not in your head, maybe you should just move on to the next problem.

If it is, then you're in luck. Without much algbra, what could the sides be?

Length * Width = Area
Width is 3 longer than length
1 * 4 = 4 < 7
2 * 5 = 10 > 7

Width must be between 4 and 5. If there are choices less than 4 or greater than 5, throw them out. They can't be right. If you still don't have the right answer, keep thinking.

Well, 4 is three less than 7 and 10 is three greater than 7. Wow! That's the same distance. It looke like 4.5 might be a good guess. If you have 4.2 or 4.7, it might be time to throw those out.

Just for the record, and it is likely that you will NOT have time for this on every problem, the exact anwer is this:

If W is the Width, then W-3 is the Length, and W*(W-3) = 7, the Area, and we have W = 4.541. I did this ONLY to suggest that the techniques and thinking shown previously are of some value. You may not be tested on the solution of quadratic equations. I'm not sure. The only way we would have failed with the approximation concepts I presented is if 4.5 and 4.6 were both on the choice list. I believe they would not do that on this exam. They are asking for an approximation.

You need to learn speed and accuracy. The art of estimation is your greatest asset. As much as it bugs me, formality is not the way to win these exams. GCSE, GMAT, LSAT - all of them. One must MOVE!!!!
 
jeff1949 said:
The area of the rectangle is 7m2

When using a keyboard, we type the caret symbol (^) to show powers:

7 m^2

This notation means that the rectangle area is seven square meters. 8-)
 
jeff1949 said:
I can see if you add the two widths, 2m each and the two lengths 1.5m [each and] then [add them] together it would make 7m squared.

No, it would not make seven square meters; it would make seven meters. (We call that the perimeter.)

You're confusing the concepts of area and perimeter. You need to memorize their definitions.
 
Jeff1949: what do you mean by "beginner"?
Are you a student attending math classes? What grade are you in?
If your kitchen floor is rectangular: 20 feet by 30 feet,
then its perimeter is 20 + 30 + 20 + 30 = 100 feet,
and its area is 20 * 30 = 600 square feet:
you seem unfamiliar with such simple basics: why?
 
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