Problem 3. A human head can be modeled as 15cm diameter sphere, with the sculp covering approximately 25%. On average adults have 100,000 scalp hairs. a) What is the density of hairs, measured as hairs per cm? b) Suppose the hairs are arranged in perfect square grid (assume the side of the square is a). What is the distance between two neighboring hairs on that grid? c) Now assume (generally not true) that a newborn has the same density of hairs as adult. How many hair will he/she have if the diameter of their head is 10cm?