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中国問題集にある問題です。どなたか教えていただけませんでしょうか。
（誤植があるかもしれませんが、原文とおりです）
1. Forty percent of the rats included in an experiment were male rats, If some of the rats died during the experiment and 30 percent of the rats that died were male rats, what was the ratio of the death rate among the male rats to the death rate among the female rats ?
A. 9/14 B.3/4 C.9/11 D.6/7 E.7/8
2. Running at the same constant rate, 6 identical machines can produce a total of 270 bottles per minute. At this rate, how many bottles could 10 such machines produce in 4 minutes ?
A.648 B.1,800 C.2,700 D.10,800 E.64,800
3. Ben and Ann are among 7 contestants from which 4 simifinalists are to be selected. Of the different possible selections, how many cotain neither Ben nor Ann ?
A.5 B.6 C.7 D.14 E.21
4. In a cetain formula, p is directly proportional to s and inversely proportional to r. If p=1 when r=0.5 and s=2, what is the value of p in terms of r, and s ?
A.s/r B.r/4s C.s/4r D.r/s E.4r/s
かっちゃん
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