Mathematics Coursework - T-totals

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GCSE MATHEMATICS COURSEWORK

T-totals

0/3/'02

Jonathan Briggs

INTRODUCTION

Introduction

The question I have been asked has been set in three parts. The question is about T-shapes on different grids. The bottom number in the T is called the T-number the T-number is the largest number in the T-shape. All the numbers in the T-shape added together are called the T-total. In the whole of the coursework you are not allowed to expand the T-shape but you are allowed to turn it around.

In part 1of my coursework I am asked to investigate the relationship between T-totals and T-numbers. At the moment I do not have any notion how the T-total could be calculated in a standard way or of the relationship between the T-number and the other numbers in the T-shape. I did know that they had to be related because they were all numbers with in a sequence. I also knew that the T-total would depend on: ~

* The position of the T-shape on the grid;

* The size of the T-shape (for the purpose of this exercise the T-shape is fixed with only five numbers);

* The orientation of the T-shape on the grid.

These points are fairly obvious as any change to the T-shape will change the numbers within it.

From this knowledge I initially experimented practically by putting T-shapes in various positions on a 9 x 9 grid. At this stage (part 1 of this paper) the T-shape was fixed in a normal T position. Part 1 shows my approach and findings from experimenting with a standard T-shape on a 9 x 9 grid

In part 2 I did further experiments with grids of different dimensions attempting to repeat my findings from part 1 with these grids and attempting to develop a general formula for grids of all sizes

In part 3 I did more experiments, this time with the T-shape in different orientations on the grid; that is on its side in two positions and upside down. I also did different vectors. This section shows new formulas and new grids.

Below are some definitions which are necessary for consistency

Definitions

: T-shape: - This is a T shape inside a grid which only contains five numbers in this case.

2: T-total: - This is all five numbers inside the T-shape added together

3: T-number: - The number at the bottom of the T-shape.

4: Other numbers: - The other numbers in the T-shape excluding the T-number

5: Number of numbers in the T-shape: - the number of numbers inside the T-shape including the T-number

PART 1

Investigating the relationship between the T-total and the T-number

Part 1

Constraints

. The T- shape cannot be expanded.

2. The T-shape cannot be moved from the standard vertical T alignment.

3. In Parts 1 - 2 the T-shape will only be able to move left and right and down and up.

4. In part 3 you will be able to twist the T-shape.

9 x 9 Grid size

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My first step to establishing the relationship between the T-total and the T-number was to draw a series of six T-shapes on the 9 × 9 grid. I then added up the numbers in the T-shape to get the T-totals. In order to find the relationship between the T-total and the T-number I divided the T-number by the T-total for each T-shape. This showed that the T-number diminished as a proportion of the T-total as the T-shape moved to the right or down the grid. I also observed that the T-total went up by five for every one position moved to the right by the T-shape on the 9 × 9 grid.

Then I found out that five (that is the number of numbers in a T-shape) times the T-number minus the sum of each of the other number in the T-shape subtracted from the T-number gave you the T-total. From this I could derive a formula.

Formula

Equation 1:~

Where ~ N = T-total

T = T-number

A = the numbers inside the T-shape taken away from the T-number

N = 5T - ((T - A) + (T - B) + (T - C) + (T - D))

: N = 5T - (4T - (A + B + C + D))

Equation 2 is a generalisation of equation 1:~

Where ~ N = T-total

T = T-number

A - N = other numbers in the T-shape

X = number of numbers in the T-shape

N = TX - (T - 1) (X) - (sum of A to N)

Equation 3: ~

Where~ N = T-total

X = number of numbers in the T-shape

G = grid size

T-total = (N) + (N - 9) + (N - 2G)

+ (N - 2G - 1) + (N - 2G +1)

T-total = 5N - 7G
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7 is the relationship of the T-total and the other numbers in the T-shape. This equation will work for different grid sizes. The only thing that will change is G, because G is the grid size.

The ratio between the T-number and the T-total reduces by four for every movement that the T-shape makes to the right.

T-total

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T-number

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Change in T-number

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Change ...

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