HI
linear equation help please...
I have plotted known numbers into an excel spreadsheet and it shows the formula as:
I am struggling to find the answer to x..??
could you go through it step by step please.....am trying to find ppm of a concentration of iron in test sample....
Concentration (ppm=mg/L) were 0 1 2 3 and 5
absorbance was 0 0.190 0.411 0.590 0.975
I graphed these in excel and these results came up y=0.1954x +0.0033
the example given at school had y=0.1954x +0.0033 (r squared =0.9993) and they came up with 2.08 ppm ......
I fail to get how they got that answer...:)
Thanks so much in advance..:)
it seems that you generated an equation for finding ppm if you know the absorbance
in the school example, there must have been an absorbance for an unknown ppm
you seem to be missing a piece of data
Sure, I can help you with that!
To find the value of x, you need to use the equation you have derived from the graph, which is y = 0.1954x + 0.0033. However, in your case, you are given the value of y and you need to find x.
Let's plug in the value of y into the equation and solve for x. From your data, you have y = 2.08 ppm.
So, the equation becomes:
2.08 = 0.1954x + 0.0033
To isolate x, you need to subtract 0.0033 from both sides:
2.08 - 0.0033 = 0.1954x
Now, you can simplify the equation:
2.0767 = 0.1954x
To solve for x, divide both sides of the equation by 0.1954:
2.0767 / 0.1954 = x
This gives you:
x = 10.630 ppm
Therefore, the concentration of iron in the test sample is approximately 10.630 ppm.
Keep in mind that the value you get may vary slightly due to rounding or other factors.