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6.唯一有个题没找到思路,蒙的。5的K次方是大约是从99到199中的奇数的乘积,包括两端,求K(答案有13,15,20之类的)想了半天没搞出来(可能理解有误,大家不要纠结。。。)某位筒子的答案是13
7.ABCDEF六个人坐一张桌子,问A和FB相邻,B和AC相邻,C和BD相邻,D和CE相邻,E和DF相邻,F和EA相邻的概率这题没思路啊排列组合太差了怎么办啊
P=2/(6-1)!=1/60
这个环形排列高考常做
满足条件的只有两种情况:
A A
F B B F
E C C E
D D
8. 2个立方体,每面都是一个数字,1-6,同时抛,问最上方的那一面数字之和是5或者9的概率多少? 5=2+3=1+4,so the probability could be 1/6 * 1/6 *2*2=1/9, 同理 9=3,6=4,5,p=1/9,so the final answer shall be 2/9.
9.to make a food, one may use chocolate and peanut, the cost of 2 pounds chocolate and 3 pounds peanut to make such a food is 3.8 per pound, if the cost of chocolate is 2 more than (or less than) that of peanut, how much does peanut cost?
10.the volume of two sphere has a ratio of 64, then what is the ratio of its surface area?
RATION 只给了一个64,另一个没给, 估计思路就是球体体积4/3 pai d³, 求出R,然后再表面积公式4 PAI R平方 比一下 |
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