1. subset(dt2, pH - 6.8) The standard curve and the line you fitted allow you to convert transmittance to haemoglobin saturation Remember the equation for a line yax+b In this case, your fitted line allows you to convert Haemoglobin Saturation to Transmittance y - Transmittance X = Haemoglobin Saturation b = Intercept from your fitted line (see Part 1c) a = Slope from your fitted Line But you need to convert from Transmittance to Hemoglobin Saturation, so you will need to solve for x in the equation for a line and use your equation to estimate Haemoglobin Saturation Instructions Assign a new column in your data frame called Hb_Saturation Use the slope and intercept for pH 6.8 and pH 74 from above: You could copy and paste the slope and intercept but its better to use the fit object's coef attribute to get your slope and intercepti intercept6.8 - fit_6.8$coef[11] slope6.8 - fit_6.85coef[1211 In