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单选题 现有10张奖券,其中8张为2元,2张为5元,某人从中随机、无放回地抽取3张,则此人所得奖金的数学期望为( )
学科：概率论与数理统计
时间：2024-03-15 13:10:21
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题目1单选题
X为随机变量,<img src="https://tihai-oss-cloud.itihey.com/img/04f4218a6d4a47bf3ccb4e35875acd35.png">,则<img src="https://tihai-oss-cloud.itihey.com/img/7229d7823c4816449384a18da6a6a226.png">=( )A. 18B. 9C. 30D. 32
题目2单选题
已知X服从参数为<img src="https://tihai-oss-cloud.itihey.com/img/ac1846e7fbfefac31ada2ac8bcda0516.png">的泊松分布,且<img src="https://tihai-oss-cloud.itihey.com/img/a31452451b5bc7b81ccf38cbe845f689.png">,则<img src="https://tihai-oss-cloud.itihey.com/img/1918d65b5b15ac6ae048979607ad9c8a.png">为( )A. 1B. -2C. <img src="https://tihai-oss-cloud.itihey.com/img/154cbb52818e2a519e4ece9c41171b4a.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/ccd129549b1d7a9724bb157766cbfbbd.png">
题目3单选题
现有10张奖券,其中8张为2元,2张为5元,某人从中随机、无放回地抽取3张,则此人所得奖金的数学期望为( )A. 6元B. 12元C. 7.8元D. 9元
题目4单选题
<img src="https://tihai-oss-cloud.itihey.com/img/53089b92bf367a4145618ed84ecb0931.png">则EY=( )A. 2B. <img src="https://tihai-oss-cloud.itihey.com/img/497bf823a153ed49ae11fa0c19f6996f.png">C. 0D. <img src="https://tihai-oss-cloud.itihey.com/img/c1d5cc30f60fcdab4b91355ef9940b91.png">
题目5单选题
随机变量<img src="https://tihai-oss-cloud.itihey.com/img/196d290d7dd457a1a883399c56a1acba.png">,则<img src="https://tihai-oss-cloud.itihey.com/img/aadc1cab9323fed4ae9bd071ee93d701.png">=( )A. <img src="https://tihai-oss-cloud.itihey.com/img/3eeda501a32eaa335a4a244d64d56989.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/286fa12b0b4572f5ace3f4e6b5be3422.png">C. 21D. 20
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