Question

A student performed an analysis of a sample forits calcium content and got the following results: 14.91%,14.89%,14.88%, and 14.90%. The actual amount of calcium in the sample is 14.90%. Calculate the percentage error and precision. Comment on the precision and accuracy of the results.


The results are precise and accurate


The results are accurate but not precise


The results are precise but not accurate


The percentage error is close to zero

Answer 1

and the precision is high, as all the measurements are very close to each other.

To calculate the percentage error, we can use the formula:

Percentage Error = [(Measured Value - True Value) / True Value] x 100

Using the given data, we get:

Percentage Error = [(14.89% - 14.90%) / 14.90%] x 100
Percentage Error = (-0.01% / 14.90%) x 100
Percentage Error = -0.067% (rounded to two decimal places)

Since the percentage error is very close to zero, we can say that the results are accurate. The precision can be calculated using the range, which is the difference between the highest and lowest values:

Range = 14.91% - 14.88%
Range = 0.03%

Since the range is very small, we can say that the results are precise. Therefore, we can conclude that the results are both accurate and precise.