SAT数学Problem Solving练习题（13）
- 2017年07月25日14:03 来源：互联网
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摘要：下面是小站SAT频道为大家整理了SAT数学Problem Solving练习题(13)，供考生们参考，以下是详细内容。
以下是小站SAT频道为大家整理了SAT数学Problem Solving练习题(13)，供考生们参考，以下是详细内容。
Question 13: Out of 25 mining companies, 14 extract copper, 16 extract silver and 1 extracts neither copper nor silver. How many companies extract both silver and copper?
(a) 1
(b) 6
(c) 2
(d) 15
(e) 3
Answer: If x is the number of companies that extract both metals,
1. the number of companies that extract copper only is 14 - x;
2. the number of companies that extract silver only is 16 - x;
There are 4 types of companies:
-that extract copper only,
-silver only,
-both copper and silver
-neither copper nor silver.
Their total should be 25:
25= 14 - x + 16 - x + x + 1
x = 31 - 25 = 6
