Question

Jenny has two scales for measuring weights in a chemistry lab. Both scales give answers that vary a bit in the repeated weighings of the same item. The true weight of compound A is 2.00 grams. The first scale in the chemistry lab produces readings where the mean of compound A is 2.00 grams with a standard deviation of 0.03 grams. The second scale’s readings have a mean of 2.001 grams and a standard deviation of 0.001 grams.

(a) Explain why it is reasonable for Jenny to assume that the two means and standard deviations are independent in this scenario.

(b) Which scale is more accurate - the first or the second? Explain how Jenny would know using statistical evidence.

(c) Find the mean and standard deviation of scale1 minus scale2. Interpret your answers.

(e) Suppose Jenny was finding the answer to Part C but instead performed the standard deviation computation for scale2 minus scale1. Would her results still be the same? Explain.

Answer 1

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