4. Let's say you have N cells, each with 100 FGF receptors. One-fifth of the 100N receptors are each occupied by a molecule of FGF. A) Find the entropy of the cell population. B) Now assume that N is a large number. Use Stirling's approximation to find the entropy of the cell population. C) If the population consists of 1000 cells, what percentage error does using Stirling's approximation give when calculating the entropy