Keeping water supplies clean requires regular measurement of levels of pollutants. The measurements are indirect-a typical analysis

Question:

Keeping water supplies clean requires regular measurement of levels of pollutants. The measurements are indirect-a typical analysis involves forming a dye by a chemical reaction with the dissolved pollutant, then passing light through the solution and measuring its "absorbance." To calibrate such measurements, the laboratory measures known standard solutions and uses regression to relate absorbance and pollutant concentration. This is usually done every day. Here is one series of data on the absorbance for different levels of nitrates. Nitrates are measured in milligrams per liter of water.

Data set
Step 1:
Chemical theory says that these data should lie on a straight line. If the correlation is not at least 0.997, something went wrong and the calibration procedure is repeated. Plot the data and ?nd the correlation. Must the calibration be done again?
Yes
No
Step 2:
The calibration process sets nitrate level and measures absorbance. Once established, the linear relationship will be used to estimate the nitrate level in water from a measurement of absorbance. What is the equation of the line used for estimation?
? = 14.522 + 8.825x
? = 14.522 ? 8.825x
? = ?14.522 ? 8.825x
? = ?14.522 + 8.825x
Step 3:
Do you expect estimates of nitrate level from absorbance to be quite accurate?
No
Yes