1.  (1/3) / (2*0.5)  # 0.3333

2.

# E(X^2) = Var(X) + (EX)^2

(2.2 + 2.2^2) / (2*2.2)  # 1.6

3.  

   f_L is approx integral( 2 t^2 / (15 (2.8)) ) from 3.2 to 4

   g <- function(s) 2 s^2 / (15 (2.8))

   integrate(f,3.2,4)  # 0.4957

4.

sim <- function(t,nreps)
{ 
  sumw <- 0.0
  for (rep in 1:nreps) {
     arrv <- 0.0
     while (1) {
        arrv <- arrv + runif(1)
        if (arrv > t) break
     }
     sumw <- sumw + arrv - t
  }
  sumw / nreps
}

set.seed(9999)
print(sim(50.0,5000))