Lily replicates an experiment that found that the number of calories in a particular food is 50 kcal. She obtained data from

five trials: 50 kcal 72 kcal, 50 kcal, 12 kcal, and 50 kcal. Which best desribes her data results? A. accurate B. incorrect C. invalid D. precise

Option A. accurate.

Explanation:

Accuracy describes how close the experimental measure is to the correct value.

In this case the number of calories found in the experiment that is being replicated would be considered as the correct value to compare: 50 kcal.

The result of the experiment carried out by Lily is the average of the five trials:

Average = ∑ measures / amount of measures

Average = [50 kcal + 72 kcal + 50 kcal + 12 kcal + 50 kcal] / 5 =

Average = 234 kcal / 5 = 46.8 kcal

Round to two significant figures:

Average = 47 kcal

Find the error:

Error = | correct value - obtained value | / (correct value) * 100 =

Error = [50 kcal - 47 kcal] / 50 kcal * 100 = 6%

That is not a big error, that drives to conclude that the data results are incorrect, so discard option B (incorrect) and it is, indeed, relatively accurate.

Precision measures how close the data obtained are close to each other. You can see that there is great dispersion, since the data are in the range [12, 72], which is too big compared with the average.

Thus, at once you can conclude that the data are not precise (option D. is discarded).

You cannot talk about validity since that is more related with the experimental procedure, so discard option C. (invalid).