Victory for the ACT Student Text 15e

V ICTORY P RACTICE T EST A NSWERS AND E XPLANATIONS • 471

15. (C) (p. 408) Science/Interpretation of Data/Comprehension . (C) is the only group in which total blood cholesterol of ͳ͸ͲȂͳͻͻ ‰Ȁ† †‡…”‡ƒ•‡• –Š‡ †‹ƒ‰‘•‹• ”ƒ–‡ ˆ‘” ƒŽŽ –Š”‡‡ ‹ŽŽ‡••‡•Ǥ –‘–ƒŽ „Ž‘‘†…Š‘Ž‡•–‡”‘Ž ‘ˆ ͳ͸ͲȂͳͻͻ ‰Ȁ† ”ƒ‹•‡• the probability of diagnosis for lung and colon cancer only. This question is probably best answered by recognizing that fact and eliminating those choices that include either lung or colon cancer: eliminate (A), (B), and (D). 16. (G) (p. 409) 6FLHQFH 6FLHQWLÀF ,QYHVWLJDWLRQ $SSOLFDWLRQ . Standardizing the diagnosis rate involves correcting for variables inherent in the subject groups but not involved in the experiment. Age, weight, and genetic histories are just some of the variables that the scientist must consider. (F) does not correct for intrinsic variables; rather, it ignores results that might not conform to a “neat” result. This does not standardize the diagnosis rate so much as “fudge” it. (H) involves an arbitrary assumption that is in fact incorrect. Assuming a zero diagnosis rate in the male population distorts the result of this experiment and does not correct for variations within the subject groups. (J) is incorrect because this experiment does not consider women at all. It might be valid to compare results with a different experiment involving women, but the actual diagnosis rates for men and women for different diseases are not necessarily similar (e.g., the gender-related differences for breast cancer). 17. (C) (p. 410) Science/Interpretation of Data/Analysis . Since voltage is directly related to current, voltage increases by the same factor as current if other variables are held constant. The same applies for resistance; therefore, the only possible correct formula is (C). 18. (F) (p. 410) Science/Interpretation of Data/Application . The total resistance R s of the series resistors is R R 2 2 4 1 2 + = + = . This resistance is double that of the circuit where R 2 . If R doubles, then the voltage doubles as long as the current remains the same. 19. (A) (p. 410) Science/Interpretation of Data/Analysis . The passage states that the voltage is directly proportional to the both the resistance and the current ( V IR ? ), so the circuit with the greater resistance would have the greater voltage. Since resistance is directly proportional to resistivity, the germanium circuit would have the greater resistance and voltage. 20. (H) (p. 411) Science/Interpretation of Data/Application . Use the given formula for resistors in parallel: R 1 4 1 4 1 = +

p

2

=

4

1

=

2

=

R

2

p

21. (A) (p. 411) Science/Interpretation of Data/Application . If R of exponential growth. 22. (J) (p. 411) Science/Interpretation of Data/Analysis .

is constant, then P

increases with I

2 Ǣ –Š‹• ‹• –Š‡ †‡ϐ‹‹–‹‘

Based on the information given in the passage, we have:

V IR I R V ? ? Therefore, to keep I

constant if V

increases, R

must be increased.

23. (D) (p. 412) Science/Evaluation of Models/Analysis . Compare Trials 2 and 3 to see what changing the concentration of only one component has on rate. In this case, there is no change in rate with change in concentration of A, so rate is independent of concentration of A. 24. (F) (p. 412) Science/Evaluation of Models/Analysis . ‘’ƒ”‡ ”‹ƒŽ• ͳ ƒ† ͵ ‘” ”‹ƒŽ• ʹ ƒ† Ͷ –‘ •‡‡ ™Šƒ–…Šƒ‰‹‰ the concentration of only one component has on rate. In this case, rate increases in direct proportion with increasing concentration of A.