(a): let x1,X2, - , X be a random sample of size n from a distribution with probability density function f) = x20 Ta8 1- Find the mean of 2x, + x2 2- Find the variance of 2x, +x3 (b): ): let Let x,X2,.,X64 be a random sample of size 64 from a normal distribution with mean-50 and variance-16. 1- find p(49 sx s 51) 3- Find p(49 sis 51 %3D (Hint: p(z s 2) = 0.9772 ,p(zs 0.25) = 0.5987 )