In March 1995 the Space Shuttle Carried an Experiment Designed $p(x)=x e^{-x}$

Essay

In March 1995 the space shuttle carried an experiment designed by a Harvard student who studies the growth of crystals.Suppose the probability density function of the length, x cm, of a crystal grown in space is modeled by $p(x)=x e^{-x}$ for $x \geq 0$ .The cumulative distribution function giving the probability that a crystal has length $\le$ t cm is represented by P(t).Which of the quantities (i)- (x)below best approximates the probability that a crystal has length between 4 cm and 4.01 cm?