<p>从总体X中抽取样本<img src="https://file.gaojiufeng.cn/learnAppQuestion/64/f7/64f76101aaa61ccb4600972548ebcfcd.jpg" style="width: 100%;height: auto;">若统计量<img src="https://file.gaojiufeng.cn/learnAppQuestion/ed/cd/edcd17c0d60c51af358fc31ddd55540e.jpg" style="width: 100%;height: auto;">是总体均值μ的无偏估计, （1）求a的值 ;（2）请比较说明估计量<img src="https://file.gaojiufeng.cn/learnAppQuestion/75/ac/75aca6394f5ac447cd8f2883870928bb.jpg" style="width: 100%;height: auto;">与估计量<img src="https://file.gaojiufeng.cn/learnAppQuestion/9b/29/9b293a886a89c04e70f8aad837ed8b34.jpg" style="width: 100%;height: auto;">哪个更有效?</p>