The following data were obtained in calibrating a calcium ion electrode for the determination of pCa. A linear relationship between the potential and pCa is known to exist.
pCa = -log [Ca2+]E, mV
5.00...............................253.8
4.00...............................227.7
3.00.................................12.7
2.00...............................131.9
1.00...............................165.1
(a) Find the least-squares expression for the best straight line among the points. Plot this line.