A researcher is developing a radioimmunoassay (RIA) to measure peptide hormone concentration in samples of human serum. Radioactivity is measured using a scintillation counter across a range of peptide hormone concentrations. The results are as follows. (a) What concentration range shows a linear relationship between peptide hormone concentration and radioactivity? (b) Develop an equation for peptide hormone concentration as a function of radioactivity within the linear range. (c) Three samples give radioactivity readings of 2.02,2.66, and 2.75. Estimate the concentration of peptide hormones present for each reading. (d) In which results from (c) do you have the most confidence? Why