Please help me with Question 3, 4, and 7. Thank you!!!

Question 3 Suppose X~Exponential(2), what is the cdf of X, Fx(x) (for x>0)? (NOT pdf) O 2e-2x O e-2x O 1-2e-2x O 1-e-2x O None of the above Question 4 Suppose the number of customer arrivals is X~Poisson(3), then the time T until the first arrival has the pdf: O fT(t)=e-3t O fr(t)=3e-3t O fr(t ) =e-t O fr(t)=e-t/3 O None of the aboveQuestion 7 1 pts Suppose that Z is the standard normal variable and X is a normal variable with mean equal to 1 and variance equal to 4, which of the following is true? X71 OZ=T X71 OZ=T _X+1 OZT ozz 0 None of the above