Practice Question Answers

Question 1: In the sample chart, we show a rate of change of about –.00328 mmol/L at 9:00 am. What does this mean about the CO2 concentration at 9:00 am?
Answer: This means that the CO2 concentration is decreasing by .00328 mmol/L per hour at 9:00am. (We would estimate that after another hour, we would have a concentration which is about .00328 mmol/L lower.)
Question 2: Based on the data in the chart, is the concentration of CO2 increasing or decreasing at 9:00 am? How can you tell this from your data?
Answer: The value you have for a rate of change at 9:00 am is negative, and therefore the concentration is decreasing at 9:00 am. Don't be fooled by the fact that the graph you see is increasing; the graph you have plotted is of the rate of change of concentration, not of the concentration itself. (In other words, your data is the derivative of the concentration.)

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