Janehasa＄15.00token(购书券)．Herearesomeofthebooksshewouldliketobuy．Whichbookswillshegetifshespends＄15.00exactly(精确地；准确无误地)?A．Schoolgirls’Life＄9.95B．ShowJumping
Jane has a ＄15 . 00 token(购书券)．Here are some of the books she would like to buy．Which books will she get if she spends ＄15 . 00 exactly(精确地；准确无误地)?
A．Schoolgirls’ Life ＄9 . 95
B．Show Jumping ＄4 . 50
C．James and the Peach ＄1 . 55
D．Pocket Book of Birds ＄2 . 95
E．Standard Dictionary ＄3 . 50
解析：
A＋C＋E (Schoolgirls’ Life 9.95＋James and the Peach 1.55＋Standard Dictionary 3.50)．
设分布列为P=1/(2^k),k=1,2.求期望..在线等E=Sigma(k/(2^k)),2*E 2020-05-13 …
纵横字谜之英语暑假作业题（s)(o)(r)(r)(n)(g)(r)(e))(a)(k)(k)(e) 2020-06-06 …
重新排列字母,写出单词1.s,a,p,e,c,2.r,o,e,t,c,k,3.d,c,o,o,t, 2020-06-06 …
概率统计随机变量及其分布问题已知随机变量X的分布律为P（X=k）=ae^-k+2（k=0,1,2· 2020-06-19 …
已知随机变量X只取非负整数,其概率分布为P（X=k）=ab^k/k!,且E(x)=入,试确定a,b 2020-07-31 …
M/P=kY-hr表示货币市场均衡,那M/P=Y的k次方乘以e的-hr（e是自然对数的底）次方表示 2020-08-02 …
设随机变量E的分布列为P{E=k}=k/15,k=1,2,3,4,5.试求:P{E=1或E=2};P 2020-11-03 …
英语：下1.将下联打乱的字母组成单词,并写出汉语意思1.a,e,h,g,c,n[]2.e,i,s,t 2020-12-10 …
随机变量X的分布列P(X=k)=ae-k（e负k次方),k=0,1,2….则a=1-e-1(e的负一 2021-01-14 …
英文单词分类填空动物类1.O()t()p()s2.k()t()e()3.l()b()t()r4.a( 2021-02-05 …