Statistic and Probability

I need quesstion 2 please

> 1. (50pts) An assembly consists of three components placed side by side in the longitudinal direction. The lengths of the components (X1, X2, and X3, respectively) are normally distributed. If the mean length of the components are u1=u2=u3 =100 mm and variances are 012-022=63212. Calculate a. The probability that the total length of the three components is less than 309 mm b. The probability that total length of the three components is in between 288 and 312 mm. c. The probability that total length of the three components is more than 315 mm. 2. (50pts) Prove that, for any X1, ..., X. 17 v(ajX1 + .+ a,xn) = {2a,a, Cov(x,x) 1=1/1