Bingo Bingo 十星的期望值是多少元?

想請問大家十星的期望值是多少元?十星就是在80個號碼裡頭選10個號碼的意思每注25元中10顆獎金5000000中9顆獎金250000中8顆獎金25000中7顆獎金2500中6顆獎金250中5顆獎金25中0顆獎金25請幫我算到小數點以下第二位採四捨五入計算
沒人答我就不客氣了！

E(x10) = C1010*C7010/C8020 * 5000000 ≒ 0.5611 ( to 4 d.p. )E(x9) = C109*C7011/C8020 * 250000 ≒ 1.5302 ( to 4 d.p. )E(x8) = C108*C7012/C8020 * 25000 ≒ 3.3855 ( to 4 d.p. )E(x7) = C107*C7013/C8020 * 2500 ≒ 4.0279 ( to 4 d.p. )E(x6) = C106*C7014/C8020 * 250 ≒ 2.8698 ( to 4 d.p. )E(x5) = C105*C7015/C8020 * 25 ≒ 1.2857 ( to 4 d.p. )E(x0) = C100*C7020/C8020 * 25 ≒ 1.1448 ( to 4 d.p. )E(x) = E(x10) E(x9) E(x8) E(x7) E(x6) E(x5) E(x0)E(x) ≒ 14.81因此

十星的期望值為 14.81 元 參考資料 http://tw.myblog.yahoo.com/jw!JCVbjQyaBRbXTWOakincl1.Wpxbobg--/article?mid=5661