设总体X与Y相互独立且均服从正态分布<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041817032257766.jpg?sign=f557d01eaa54038f8e8deb451e1a3366&t=62d7a1a9" />分别为来自X与Y的样本，则统计量<img src="https://nimg.ppkao.com/2019-04/wuacheng/2019041817034190515.jpg?sign=684544889d77799f664be13a9ba1fe23&t=62d7a1a9" />服从什么分布？