Calibration procedure: The transfer function for this problem is of the form Y = bX + c where the slope of the line (b) is (Y2-Y1)/(X2-X1) = b (20-0)/(40-0) = 0.5 and the Y-intercept (c) is ((Y2+Y1)/2) - b * (X2+X1)/2 = c 20/2 - 0.5 * 40/2 = c 10 - 10 = 0 therefore the transfer function is Y = 0.5 * X + 0 12.5^{o}C = 0.5 * 25 + 0 and for 25%Globegerinathe sea-surface temperature was 12.5^{o}C