本题目来源于试卷: Photochemical Smog，类别为 IB环境系统与社会
[单选题]
Figure: Standards for PM10 air pollut c*dwpvxatui(zq,8 8qc otw8/+fe*k1antsai :oej(qcuf 7k8x k(1
WHO /$\mu$gm EU /$\mu$gm USA $\mu$gm
-3 -3 -3
24hours 24hours 24hours
−1 −1 −1
45 50 50
Calculate the percentage difference between the WHO guideline standards and the USA standards.
A. 105
B. 233
C. 70
D. 333
参考答案: D
本题详细解析:
% difference =$\frac{new value - initial value}{initial value}$×100 =$\frac{150-45}{45}$×100 = 233%
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