AccelePrep for the ACT Test 2nd Edition Student Text

C HAPTER 5 | H YPER P REP M ATH • 109 8. —•– Ž—‰Ǧƒ†Ǧ Š—‰Ǥ Š‘‘•‡ ƒ ˜ƒŽ—‡ ˆ‘” x , say 4. What is the cost of a call lasting exactly 4 minutes? The cost of dialing is $0.15, and the cost of the connection time is 4($0.04) = $0.16. So the total cost is $0.15 + $0.16 = $0.31. Now substitute 4 for x into the answer choices. The correct answer will return the value $0.31: F. ( . . ) . y 4 0 04 0 15 0 76 G. . . . y 0 04 4 0 15 0 31 ^ h H. . . . y 0 04 0 15 4 0 64 ^ h Ǥ . . . y 0 15 0 04 4 0 01 ^ h K. . . . y 0 04 0 15 4 0 56 ^ h 9. Solve this problem by assuming some numerical values for a and b . You may have to try a couple of different values, but the method is very reliable. For example, try a = –1 and b = –1: A. a b 1 1 0 ^ ^ h h (Not positive, so wrong) B. a b 1 1 0 ^ h (Not positive, so wrong) C. a b 1 1 0 (Not positive, so wrong) D. a b 1 1 2 (Not positive, so wrong) E. Correct by the process of elimination: a b 1 1 2 ^ ^ h h (Positive in this case, so check) 10. You can most certainly use the procedures for manipulating the equation to solve for x . But there is another alternative: Test-the-Test. ‡ ‘ˆ –Š‘•‡ ϐ‹˜‡…Š‘‹…‡• ‹• –Š‡ ˜ƒŽ—‡ ‘ˆ x , so just plug the choices into –Š‡ “—‡•–‹‘ ƒ† †‘ –Š‡ ƒ”‹–Š‡–‹…—–‹Ž ›‘— ϐ‹† –Š‡…‘””‡…– ‘‡Ǥ F. 2 2 5 3 7 2 5 5 d d n n 5 3 2 35 5 2 45 (Wrong) Š‡ ϐ‹”•– ’Ž—‰Ǧ‹ ”‡–—”• ƒ ˆƒŽ•‡ •–ƒ–‡‡–ǡ •‘ ȋ Ȍ ‹• ™”‘‰Ǥ ˆ ›‘— †‘ –Š‡ ƒ”‹–Š‡–‹…ˆ‘” ȋ Ȍ ƒ† ȋ Ȍǡ ›‘—ǯŽŽ ϐ‹† –Šƒ– –Š‘•‡…Š‘‹…‡• ƒŽ•‘ ”‡–—” ˆƒŽ•‡ •–ƒ–‡‡–• ƒ† —•– „‡ ™”‘‰Ǥ Š‡ ›‘— ™‘—Ž† –”› ȋ Ȍǣ Ǥ 2 5 2 3 7 5 2 5 c c m m 5 4 3 5 14 5 5 11 (Correct) Since the value for x ‰‹˜‡ ‹ ȋ Ȍ ”‡–—”• ƒ –”—‡ •–ƒ–‡‡–ǡ ȋ Ȍ ‹• –Š‡ right answer. 11. —•– ‡•–Ǧ–Š‡Ǧ ‡•–ǣ A. 32 16 0 2 (Wrong) B. 16 16 0 2 (Wrong) C. 8 16 0 2 (Wrong) D. 4 16 0 2 (Correct) So (D) is the correct answer. 8 5 11

CLOSER LOOK Remember that 0 is neither positive nor negative.