In a consumer survey, 85% of those surveyed liked at least one of three products: 1, 2, and 3. 50% of those asked liked product 1, 30% liked product 2, and 20% liked product 3. If 5% of the people in the survey liked all three of the products, what percentage of the survey participants liked more than one of the three products?
A) 5
B) 10
C) 15
D) 20
E) 25
答案说是B作者: nbnhjf 时间: 2004-8-23 07:28
all dislike : 15%
Like 1 : 50%
Like 2 : 30%
Like 3 : 20%
You could draw 3 circles , and they will have overlapped area .
In Like 1 area , you could separate :
Like 1 only : a% , Like 1&2 : d% , Like 1&3 e%
In Like 2 area : Like 2 only : b% , Like 2&3 f%
In Like 3 area : Like 3 only : c%
So you will have 6 variables : a/b/c/d/e/f
And you will get 4 equation :
a+d+e+5=45 ; b+d+f+5=30 ; c+e+f+5=20 ; a+b+c+d+e+f+5=85
For the first 3 equation , you could choose 2 of 3 add together , and use the last equation to minus , you will get
a-f=40 ; c-d=10 ; b-e=20
Then you could substitue a/b/c with f+40/e+20/d+10 into the last equation
You will get 2(d+e+f)=10 , so you will know d+e+f+5=10%--Ans
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