2. Mean and variance. [a] Express Var{X1 + X2} through the variances and eevarianes nf X11X3 (assuming ail variances exist]. [h] Suppdse that X1. . . . In are i.i.d. real-vniued random variables with nite variances. Shaw that \"EC 21') =var[ {1'1}. [e] Assume that IJ' are independent random variables with ELK} = l1. E'] = l, Var{X] = 1, Var") = 2. Cnmpnte E {EEK + YHEY + 23'." 1}]