Solution

ID: past-exam-of-the-probability-statistics-and-options-ii-course-of-the-university-of-oxford/2010/o/o4/b/ii/solution

A linear combination of independent normal random variables is normal, with variances adding when the coefficients are . Applying the joint central limit approximation from (i) gives
Equivalently the difference minus , divided by the displayed standard deviation, converges in distribution to a standard normal under the same regular large-sample regime.

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