38)应用题,A的篮子里有1个chicken sandwich和2个cheese sandwich。B有3个chicken sandwich和5个cheese sandwich。问BOTH A AND B 随机取出的是chicken sandwich的概率是多少?
(1/3)*(3/8)=1/8,数字不确定。
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to mingja
两个人分别完成某项任务,A用了X小时,B比A快两倍,问in term of X,两个人一起完成这项任务要用多久? 答案是2X/3
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my ans is x/3
1/[(1/x)+(2/x)]
the ans must be wrong , since it's impossible that two of the guy spend longer time to do the things than one of the guys does
2. still number discussion , i think it is A
3某东西sell at price 20 dollors, including tax, 税率是百份P,还包括其他什么费less than C,好象问:不含税的部分小于15吗?A:P等于6,B:C等于5
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(x+c)(1+p)=20
my ans is B
4. 有一个长方形,长是12,宽是18,现在扩大多少倍?问现在的宽是多少?
A:长扩大多少倍 B:宽扩大多少倍?
答案肯定是D
agree D
(12+x)(18+y)=12*18*# ( # should be known though the problem is incomplete)
5. 有某个地方的用电量1993年是3.2million 而1993年是3.4million,他们用柱壮图来表示,用电量与柱高成正比例,1993年的柱高是2cm,问:1994年的柱高是多少?
答案:3.2/2=3.4/x x=9/4
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agree , the ratio of the height in the graph and the amount consuming is unchanged
3某东西sell at price 20 dollors, including tax, 税率是百份P,还包括其他什么费less than C,好象问:不含税的部分小于15吗?A:P等于6,B:C等于5
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(x+c)(1+p)=20
my ans is B
3某东西sell at price 20 dollors, including tax, 税率是百份P,还包括其他什么费less than C,好象问:不含税的部分小于15吗?A:P等于6,B:C等于5
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(x+c)(1+p)=20
if c=5 , whatever p is , ( even is 0 ) x<=15 , but from the text , p can not be 0 , since there is tax payment ( or you will be fined ....kidding ) so B is sufficient
but when p=6 or mean tax rate 6%
x+c about 19 , x can be less or more than 15
^^