A student performed an anaysis of a samply for its calcium content and got the following results :
14.92% , 14.91%, 14.88% , 14.91%
the actualy amount of calcium in te sample is 15.70%. What conclusion can you draw about the accuracy and precision of these results?
--im really confused with this problem for some reason. please help me.
Accuracy is how close the analyst is to the actual value. The precision is how close the repetitive values are to each other.
consider a .90 M Al(NO3)3 solution. what is the molar concentration of nitrate ion in this solution?
Shanta, please go to the top of the page and click on post a new question. Post a question in your name instead of an answer to another problem. Since there are three nitrate ion per mole of Al(NO3)3, then the nitrtion concn is ??
To assess the accuracy and precision of the results, we need to examine the terms and analyze the data. Accuracy refers to how close the measured values are to the true or target value, while precision represents the consistency or reproducibility of the measurements. Let's analyze the given data:
- Measured values: 14.92%, 14.91%, 14.88%, 14.91%
- Actual value: 15.70%
First, we will look at accuracy. The measured values are consistently lower than the actual value of 15.70%. This indicates a systematic error in the measurement process, as the values consistently underestimate the true amount of calcium. The accuracy, therefore, is relatively low.
Next, let's consider precision. Precision refers to the consistency or reproducibility of the measurements. To assess this, we can calculate the mean (average) and the range (the difference between the highest and lowest values).
Mean:
(14.92% + 14.91% + 14.88% + 14.91%) / 4 = 14.905%
Range:
Highest value: 14.92%
Lowest value: 14.88%
Range: 14.92% - 14.88% = 0.04%
The mean value reflects the average calcium content of the samples, which is 14.905%. The range shows the spread or variability of the measurements, which is 0.04%.
Since the range is relatively small, it suggests good precision. However, we should consider precision in relation to accuracy. In this case, the results are not accurate but do indicate good precision (low variability) because the range is small.
In conclusion, the analysis of the sample for calcium content shows low accuracy (results consistently lower than the actual value) but good precision (low variability).