Mathematics 30 June 1999 Grade 12 Diploma Exam
Mathematics 30 June 1999 Grade 12 Diploma Exam
Mathematics 30 June 1999 Grade 12 Diploma Exam
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19. If log 2 b = c , then log 4 b equals<br />
A.<br />
c<br />
2<br />
B. c 2<br />
C. 2c<br />
D. c<br />
20. The lead concentration of human blood, C B , measured in µg/100 mL, increases<br />
with the mean lead concentration of the environmental air to which a person is<br />
exposed, C L , measured in µg/m 3 , according to the formula C B = 60 log C L – 20.<br />
If the lead concentration of samples of environmental air has values between<br />
5.0 and 100.0 µg/m 3 , then the range of lead content in human blood is<br />
A. 21.9 to 100.0 µg/100 mL<br />
B. 20.0 to 60.0 µg/100 mL<br />
C. 2.6 to 100.0 µg/100 mL<br />
D. 2.1 to 6.0 µg/100 mL<br />
<strong>12</strong>
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