his doesnt inspire any confidence that it is correct. Question says S = sqrt(4n).(Xn-u) but this solution starts with S= 4n.(Xn-u)   ? No explanation of how Var[4n(Xn-u)] becomes 4n2Var(Xn)    : I get that u is constant but whats happening to 4n ->4n2 ? No explanation of how 4n2Var(X/n) becomes 16.sigma2/n    : I get that Var(X) is given as sigma2, but the rest?

This doesnt inspire any confidence that it is correct.

Question says S = sqrt(4n).(X_n-u) but this solution starts with S= 4n.(X_n-u)   ?

No explanation of how Var[4n(X_n-u)] becomes 4n²Var(X_n)    : I get that u is constant but whats happening to 4n ->4n² ?
No explanation of how 4n²Var(X/n) becomes 16.sigma²/n    : I get that Var(X) is given as sigma^2, but the rest?