从均值为20，标准差为10的总体中抽取一个容量为100的随机样本，则样本均值的抽样分布为（）。
未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_9b144020-3998-474d-8a1e-1f998802197e.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_0bb33937-28d8-4b2b-9a48-b09377c983fd.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_bd977a22-7b95-404e-875e-7fc630dbe3bc.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_d6aba568-f778-4d7e-b09a-a270c57ae4cf.png"]'], 'type': 102}
未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_9b144020-3998-474d-8a1e-1f998802197e.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_0bb33937-28d8-4b2b-9a48-b09377c983fd.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_bd977a22-7b95-404e-875e-7fc630dbe3bc.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_d6aba568-f778-4d7e-b09a-a270c57ae4cf.png"]'], 'type': 102}
举一反三
- 设[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_067016aa-77f2-4aff-bd36-e3fa5f1bd893.png"],[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_358ab06c-7f19-4ae6-ba82-424c72bd4d18.png"],则[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_2b561af0-b65d-4e5e-936b-72b15b4f0f56.png"][img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_92284d1b-6fe3-4dc1-a732-618796cd01a4.png"] A: 6 B: 10 C: 8 D: 4
- 设三阶方阵A的秩是2，则与A等价的矩阵为（ ） 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_2a68ab7b-9b7e-4607-abde-e255189c845c.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_208fb5a8-85c0-4a53-8cf2-673752bf5034.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_08c0964d-f78b-44eb-ac06-5c18ec1142e0.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_3d5b7bfd-bef2-4920-8749-90e0f59a4770.png"]'], 'type': 102}
- 设A，B为任意两个n阶方阵，则下列一定成立的是 （ ） 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_33399133-78a2-46d1-b0e6-585d3e1a61fa.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_d308b840-8167-4c60-98c2-50ad54a58d80.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_0836c6f0-9141-4013-8ffa-bd3be454df0a.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_46c561a2-1836-4982-9c80-e1bbc2dc9af1.png"]'], 'type': 102}
- 下列矩阵，哪一个是正交矩阵（ ） 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_e3bcbe32-bf4f-4dd7-87eb-435166d4a694.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_2dd5a805-5f17-4578-950f-b0e99cb4ace5.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_fb404ce8-29fb-4a21-9f66-2e1cc1e8e6b2.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_6238ef9e-3ec5-4c01-8429-4fbbb82bc5ff.png"]'], 'type': 102}
- 设某种气体的分子速率分布函数为f(v),则速率在v1-v2区间内的分子平均速率为 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_4c30e9fe-5d04-4fc8-9957-2805655c8cf0.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_e46a2d3c-c302-4e0e-b7f1-dbda05263391.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_236231d7-a42e-4a27-ad17-4fa25ffa0243.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_aa7899be-ed45-4d9c-a3c7-785ff01d6664.png"]'], 'type': 102}