设总体‍<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/7e4da83fcd564aebad28b5c1224c6d2a.png?x-oss-process=image/sharpen,200"/>，<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/0c189427505743a7b08b9c2cf82e4a91.png?x-oss-process=image/sharpen,200"/>是从总体<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/ac47cd54f73d4ea9a6851cdfa1d1b104.png?x-oss-process=image/sharpen,200"/>中抽取的样本，记<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/803d1c9bd0bd483e923e8f74e6199dec.png?x-oss-process=image/sharpen,200"/>，则记，则<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/33a97cc75d7142ae984da3dd3c02a0eb.png?x-oss-process=image/sharpen,200"/>的值( )。