- #1

- 115

- 5

Here are the points:

10 - 54

20 - 216

30 - 486

40 - 864

50 - 1350

60 - 1944

70 - 2646

80 - 3456

90 - 4374

Thanks.

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- Thread starter beamthegreat
- Start date

- #1

- 115

- 5

Here are the points:

10 - 54

20 - 216

30 - 486

40 - 864

50 - 1350

60 - 1944

70 - 2646

80 - 3456

90 - 4374

Thanks.

- #2

- 66

- 24

Hint: In general you'd get an equation of the form y = ax

Also note: Now that I've told you it's quadratic, you could of course just ask your software for the solution. Don't cheat yourself! Use google to look into the method I mentioned above, and take the first step toward arming yourself to deal with such problems in the future.

- #3

HallsofIvy

Science Advisor

Homework Helper

- 41,847

- 966

- #4

- 132

- 4

The best recommendation I can give is for Excel 2007 on a PC. I would enter the data into the spreadsheet, then highlight the data, and create a scatter-plot chart. Select the chart, and choose the Layout Tab from the Chart Tools category. There should be a button that says "Trendline". Choose "More Trendline Options".

Select Polynomial Order 2. There's also a check box for "Display Equation on Chart". That will give you the equation.

Note: you can look at other types of trendlines and polynomials to see what would be a best fit.

Another analysis you can do in Excel is to calculate the differences of the successive range values. Then calculate the differences of those differences. For you're data, I got:

10 54

20 216 162

30 486 270 108

40 864 378 108

50 1350 486 108

60 1944 594 108

70 2646 702 108

80 3456 810 108

90 4374 918 108

Note how the difference of the differences is 108 in every case. You can use this type of information to figure out the type of equation too.

- #5

- 12,134

- 161

It's a lot easier if you can work with smaller numbers, which we can do in this case. The *x* values are all multiples of 10, so you might as well just use 1, 2, 3, ... 9 instead of 10, 20, etc. This is just easier to work with.

Also, the*y* values are all even numbers, so could obviously be divided by 2. Looking more carefully, they turn out to be divisible by 9 as well. So divide all the *y* values by 18. There might turn out to be yet more common factors to divide the *y* values down.

So the first two*y* values become 3 and 12 (54/18 and 216/18). Hmmm, wonder if there is another common factor of 3 here? If we divide all the *y* values by 3 *and* 18 -- in other words, divide them all by 54 -- then a very clear pattern becomes evident.

Also, the

So the first two

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