Question

Difficulty: MediumCalculating with Data

A group of biochemical researchers measured the enzymatic breakdown rate of cellulose (in mg/Lmin\text{mg/L}\cdot\text{min}) by three bacterial strains (Strain X, Strain Y, and Strain Z) across three different pH environments (5.05.0, 6.06.0, and 7.07.0) at a constant temperature of 37C37^\circ\text{C}. The results are recorded in the table below:

StrainBreakdown Rate at pH 5.05.0Breakdown Rate at pH 6.06.0Breakdown Rate at pH 7.07.0
Strain X121218182424
Strain Y151525253535
Strain Z8814142020

True or False: The average enzymatic breakdown rate across all three pH environments for Strain Y is 5 mg/Lmin5\text{ mg/L}\cdot\text{min} greater than the average breakdown rate for Strain X.

Answer: Answer

Answer

The statement is False because the average breakdown rate for Strain Y (25 mg/Lmin25\text{ mg/L}\cdot\text{min}) exceeds that of Strain X (18 mg/Lmin18\text{ mg/L}\cdot\text{min}) by 7 mg/Lmin7\text{ mg/L}\cdot\text{min}, not 5 mg/Lmin5\text{ mg/L}\cdot\text{min}.
The correct response is False because computing the mean breakdown rates yields 18 mg/Lmin18\text{ mg/L}\cdot\text{min} for Strain X and 25 mg/Lmin25\text{ mg/L}\cdot\text{min} for Strain Y. Subtracting 1818 from 2525 gives a difference of 7 mg/Lmin7\text{ mg/L}\cdot\text{min}, rendering the statement claiming a difference of 5 mg/Lmin5\text{ mg/L}\cdot\text{min} mathematically incorrect.

Step-by-Step Solution

1
Calculate the average breakdown rate for Strain X across all three pH levels.
Average for Strain X = 12+18+243=543=18 mg/Lmin\frac{12 + 18 + 24}{3} = \frac{54}{3} = 18\text{ mg/L}\cdot\text{min}.
To determine the overall mean performance of Strain X across the tested environments.
2
Calculate the average breakdown rate for Strain Y across all three pH levels.
Average for Strain Y = 15+25+353=753=25 mg/Lmin\frac{15 + 25 + 35}{3} = \frac{75}{3} = 25\text{ mg/L}\cdot\text{min}.
To determine the overall mean performance of Strain Y across the tested environments.
3
Subtract the average rate of Strain X from the average rate of Strain Y.
Difference = 2518=7 mg/Lmin25 - 18 = 7\text{ mg/L}\cdot\text{min}.
To test the claim that the average for Strain Y is 5 mg/Lmin5\text{ mg/L}\cdot\text{min} greater than Strain X.

Key Concept

Calculating mean values from tabular experimental data and finding differences between summary statistics.
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