Near-infrared spectroscopy (NIRS) is an analytical method that uses electromagnetic spectrum from 780 nm to 2500 nm in various non-destructive measurement applications. The measured signal of five wavelengths are tabulated in the Table To improve the quality of the NIRS signals, the rate of change can be computed to eliminate unwanted signals. Wavelength, x (nm) Measured Signal, E(x) (unit) Table 750 12.34 900 87.23 950 1000 1150 332.12 455.74 429.41 By applying all appropriate numerical first order derivative methods to the following questions: (ii) Estimate the rate of change of the signal when the wavelength was 950 nm using an interval of 200 nm. (iii) Identify the best method in estimating the rate of change of the signals with a concise justification if the exact solution is 2.4566