下面就讓小編來為大家介紹一下這幾道ACT數(shù)學(xué)習(xí)題的相關(guān)內(nèi)容吧，大家要好好把握，認(rèn)真練習(xí)，希望能夠給準(zhǔn)備參加ACT考試的同學(xué)帶來幫助。
  1. 3×3·2x2y·4x2y is equivalent to:
  A. 9x7y2
  B. 9x12y2
  C. 24x7y2
  D. 24x12y
  E. 24x12y2
  解析：The correct answer is C. To find an equivalent expression, you can multiply the constants (3·2·4), combine the x term (x3x2x2 → x3+2+2 → x7, because when you have a common base you use the base and add the exponents), and combine the y terms (y·y → y1y1 → y1+1 → y2). The result is 24x7y2.
  正確答案選C。常數(shù)相乘(3·2·4)，合并x項(xiàng)(x3x2x2 → x3+2+2 → x7) 和y項(xiàng)(y·y → y1y1 → y1+1→ y2)，結(jié)果為24x7y2。
  2. Mr. Dietz is a teacher whose salary is $22,570 for this school year, which has 185 days. In Mr. Dietz’s school district, substitute teachers are paid $80 per day. If Mr. Dietz’s takes a day off without pay and a substitute teacher is paid to teach Mr. Dietz’s classes, how much less does the school district pay in salary by paying a substitute teacher instead of paying Mr. Dietz’s for that day?
  F. $ 42
  G. $ 80
  H. $ 97
  J. $105
  K. $122
  解析：The correct answer is F. To find Mr. Dietz’s pay per day, you can divide his salary, $22,570, by the number of days he works,185. His pay per day is 22570/185, or $122. When Mr. Dietz takes a day off without pay and the school pays a subsititute $80, the school district saves the difference in these amounts, 122-80, or $42.
  正確答案選F。先算出Dietz先生每天的平均工資，用22570除以185(可用計(jì)算器)，即122美元。再用122美元減去學(xué)校需要支付臨時(shí)老師的費(fèi)用80美元，即可算出學(xué)校結(jié)余的費(fèi)用，為42美元。
  3. So far, a student has earned the following scores on four 100-point tests this grading period:65,73,81, and 82. What score must the student earn on the fifth and last 100-point test of the grading period to earn an average test grade of 80 for the 5 tests?
  A. 75
  B. 76
  C. 78
  D. 99
  E. The student cannot earn an average of 80.
  解析：The correct answer is D. To find what the student needs to score on the fifth 100-point test to average a score of 80, you need to find the point total for the student so far by adding 65,73, 81 and 82. That sum is 301. Averaging 80 points on 5 tests means the student must earn 400 points (80·5). The acore needed on the last test is the difference,400——301, or 99.
  正確答案選D。該學(xué)生前四次共得301分;5次考試平均分為80，意味著5次考試總分需達(dá)到400分，那么該學(xué)生最后一次考試需要達(dá)到的分?jǐn)?shù)為400與301的差，即99分。
  4. A rectangular lot that measures 150 ft by 200 ft is completely fenced. What is the approximate length, in feet, of the fence?
  F. 300
  G. 350
  H. 400
  J. 700
  K. 1,400
  解析：The correct answer is J. To find the length of fence needed to fence a rectangular lot 150 ft by 200 ft, you need to find the perimeter. The formula for the perimeter of a rectangle is 2 times the sum of the length and width, or P = 2( l+ w). 2(150 +200) =2(350) =700.
  正確答案選J。所需籬笆的長度即為這塊長150英尺寬200英尺矩形土地的周長。根據(jù)矩形周長公式，可知：矩形周長=2(長+寬)，即2(150 +200) =2(350) =700英尺。
  5. The expression a[b+(c-d)] is equivalent to:
  A. ab + ac – ad
  B. ab + ac + ad
  C. ab + ac – d
  D. ab + c + d
  E. ab + c – d
  解析：The correct answer is A. To find an equivalent expression, multiply a by b+c-d. This results in a(b) + a(c) + a(-d), or ab + ac – ad.
  正確答案選A。根據(jù)乘法分配率展開括號(hào)可得ab + ac – ad。
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