I have to find the percentage of error. The accepted value is 11.35, while the value I got is 2.564. I got 2.564-11.35/11.35, and got a negative answer. Can percentages of error be negative? Thanks-Coralie.
The reason that your value is negative is that, it depends on which number you put first, when subtracting the accepted value from the experimental actual value, you have to put a | | (absolute sign) around the subtracted values. (that means that the value is accepted as being possitive,even if the value comes out negative because the actual experimental value was smaller than the accepted value.
so it comes out as..
| 2.564- 11.35|/11.35 x 100 = 77.41% error
It can't be negative.
Some profs like to use the absolute value so they always subtract the larger number minus the smaller number (so as to get a positive value) and divide by the accepted value and that times 100. The same rational applies to using the | | to obtain the absolute value as Christina has answered. But to answer your question, yes, there can be a negative value. And some profs like to use the negative value so they ALWAYS subtract it this way.
[(exp value - accepted value)/accepted value]*100 which ALWAYS gives a negative value if the experimental value is lower than the accepted value and ALWAYS gives a positive value if the experimental value is higher than the accepted value. The rationale of those profs is that the sign (negative or positive) tells them immediately if the result was too high or too low. I never worried about that piece of information because if it was in error more than about 0.2% to 0.4%, that was too much for me and I started over. I hope I didn't provide far more information than you wanted.
To find the percentage error, you need to follow a specific formula. The formula for percentage error is:
Percentage Error = [(Experimental Value - Accepted Value) / Accepted Value] x 100
Let's calculate the percentage error using the correct formula:
Percentage Error = [(2.564 - 11.35) / 11.35] x 100
Percentage Error = (-8.786 / 11.35) x 100
Percentage Error = -0.7745 x 100
Percentage Error = -77.45%
The negative sign indicates that your experimental value is lower than the accepted value. Percentages of error can indeed be negative, depending on whether the experimental value is higher or lower than the accepted value.
To find the percentage of error, you should first calculate the difference between the accepted value and the measured value. In this case, the difference is 11.35 - 2.564 = 8.786.
Then, divide this difference by the accepted value and multiply by 100 to express the error as a percentage:
Percentage of Error = (|Measured Value - Accepted Value| / Accepted Value) * 100
So, in this case, the percentage of error would be (8.786 / 11.35) * 100 ≈ 77.42%.
Now, addressing your concern about the negative answer, the absolute value in the formula ensures that the result is always positive. The absolute value is denoted by using "|" around the term. So, it would be incorrect to have a negative percentage of error. If you obtained a negative result, it might be due to an error in your calculations or formula usage.
Make sure you properly place parentheses in your calculation to ensure the right order of operations. In your case, the correct formula would be (2.564 - 11.35) / 11.35.
Using this corrected calculation, you would get a positive result, and the percentage of error would be approximately 77.42%.