probability calculations

probability calculations

Suppose that F is a cumulative distribution function, where
F(x) = 0, if X<0 = 1-exp(-x), if 0 <= X <1 = C, if 1<= X <2 = 1-exp(-x),
if X>= 2
i. Find all possible values of c.
ii. Find P(0.5 <= X <= 2.5) and P(X =1) + P(X =2) .