1- Choice C is correct
The correct answer is 39 \ π cm^2 To find the area of the shaded region, find the difference of the area of two circles. (S_{1}: the area of bigger circle. S_{2}: the area of the smaller circle) Use the area of circle formula. S = π \ r^2 S_{1} \ - S_{2} = π \ ( 5 \ + \ 3cm)^2 \ - \ π \ (5 cm)^2 ⇒ S_{1} \ - S_{2} = π \ 64 cm^2 \ - \ π \ 25 cm^2 ⇒ S_{1} \ - S_{2} = 39 \ π cm^2
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2- Choice D is correct
The correct answer is \frac{5}{8} William ate \frac{1}{4} of 8 parts of his pizza that it means 2 parts out of 8 parts ( \frac{1}{4} of 8 parts = x ⇒ x = 2) and left 6 parts. Ella ate \frac{1}{2} of 8 parts of her pizza that it means 4 parts out of 8 parts ( \frac{1}{2} of 8 parts = x ⇒ x = 4) and left 4 parts. Therefore, they ate (4 \ + \ 2) parts out of (8 \ + \ 8) parts of their pizza and left (6 \ + \ 4) parts out of (8 \ + \ 8) parts of their pizza. It means: \frac{ 10}{16} After simplification we have: \frac{5}{8}
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3- Choice D is correct
The correct answer is 48 \ x^8 \ y^6 Simplify. 3 \ y^2 \ (2 \ x^2 \ y)^4= 3 \ y^2 \ (16 \ x^8 \ y^4 ) = 48 \ x^8 \ y^6
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4- Choice D is correct
The correct answer is 17 cm Use Pythagorean Theorem: a^2 \ + \ b^2 = c^2 8^2 \ + \ 15^2 = c^2 ⇒ 64 \ + \ 225 = c^2 ⇒ c^2 =289 ⇒ c=17
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5- Choice B is correct
The correct answer is 0.88 D To find the discount, multiply the number by (100\% \ – rate of discount). Therefore, for the first discount we get: (D) (100\% \ – \ 20\%) = (D) (0.80) = 0.80 D For increase of 10\%: \ (0.80 D) (100\% \ + \ 10\%) = (0.85 D) (1.10) = 0.88 D = 88\% of D
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6- Choice D is correct
The correct answer is – \ 126 Use PEMDAS (order of operation): \left[ \ 6 \ × \ (– \ 24) \ + \ 12 \ \right] \ – \ (4) \ + \ \left[ \ 4 \ × \ 5 \ \right] \ ÷ \ 2 = \left[ \ – \ 144 \ + \ 12 \ \right] \ – \ 4 \ + \ \left[ \ 20 \ \right] \ ÷ \ 2 = \left[ \ – \ 144 \ + \ 12 \ \right] \ – \ 4 \ + \ 10 = \left[ \ – \ 132 \ \right] \ – \ 4 \ + \ 10 = \left[ \ – \ 132 \ \right] \ – \ 4 \ + \ 10 = – \ 126
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7- Choice B is correct
The correct answer is 16 \ π Use the formula of areas of circles. Area = π \ r^2 ⇒ 64 \ π = π \ r^2 ⇒ 64 = r^2 ⇒ r = 8 Radius of the circle is 8. Now, use the circumference formula: Circumference = 2 \ π \ r = 2 \ π \ (8) = 16 \ π
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8- Choice B is correct
The correct answer is 30\% Use the formula for Percent of Change \frac{New \ Value-Old \ Value}{Old \ Value} \ × \ 100\% \frac{28 \ - \ 40}{40} \ × \ 100\% = \ – \ 30\% (negative sign here means that the new price is less than old price).
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9- Choice C is correct
The correct answer is 140\% The question is this: 1.75 is what percent of 1.25? Use percent formula: part = \frac{percent}{100} \ × whole = \frac{percent}{100} \ × 1.25 ⇒ 1.75 = \frac{percent \ × \ 1.25}{100} ⇒ 175 = percent × \ 1.25 ⇒ percent = \frac{175}{1.25} = 140
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10- Choice A is correct
The correct answer is 10\% Let x be the amount of students in the class. 40\% of x = girls 25\% of girls = tennis player Find 25\% of 40\%. Then: 25\% of 40\%=0.25 \ × \ 0.40=0.10=10\%
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11- Choice B is correct
The correct answer is 28 Write the numbers in order: 2, \ 19, \ 28, \ 28, \ 35, \ 44, \ 67 Since we have 7 numbers (7 is odd), then the median is the number in the middle, which is 28.
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12- Choice C is correct
The correct answer is 60000 Three times of 24,000 is 72,000. One sixth of them cancelled their tickets. One sixth of 72,000 equals 12,000 (1/6 \ × \ 72000 = 12000). 60,000 (72000 \ – \ 12000 = 60000) fans are attending this week
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13- Choice A is correct
The correct answer is 7 Write the ratio and solve for x. \frac{45}{40} =\frac{2 \ x \ + \ 4}{16} ⇒ 40 \ (2 \ x \ + \ 4)=45 \ × \ 16 ⇒ x=7
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14- Choice B is correct
The correct answer is 8 \ (4 \ − \ x)=96 Only option B is correct. Other options don’t work in the equation. 8 \ (4 \ - \ (- \ 8))=96
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15- Choice A is correct
The correct answer is 8 Let x be the number of balls. Then: \frac{1}{3} \ x \ + \ \frac{1}{6} \ x \ + \ \frac{1}{4} \ x \ + \ 12 = x (\frac{1}{3} \ + \ \frac{1}{6} \ + \ \frac{1}{4}) \ x \ + \ 12 = x (\frac{9}{12}) \ x + 12 = x x = 48 In the bag of small balls \frac{1}{6} are white, then: \frac{48}{6} = 8 There are 8 white balls in the bag.
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16- Choice B is correct
The correct answer is 50 Use the information provided in the question to draw the shape. Use Pythagorean Theorem: a^2 \ + \ b^2 = c^2 40^2 \ + \ 30^2 = c^2 ⇒ 1600 \ + \ 900 = c^2 ⇒ 2500 = c^2 ⇒ c = 50
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17- Choice B is correct
The correct answer is 15\% The question is this: 530.40 is what percent of 624? Use percent formula: part = \frac{percent}{100} \ × whole 530.40 =\frac{ percent}{100} \ × 624 ⇒ 530.40 = \frac{percent \ × \ 624}{100} ⇒ 53040 = percent × \ 624 ⇒ percent = \frac{53040}{624 }= 85 530.40 is 85\% of 624. Therefore, the discount is: 100\% \ – \ 85\% = 15\%
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18- Choice B is correct
The correct answer is 15 If the score of Mia was 60, then the score of Ava is 30. Since, the score of Emma was half as that of Ava, therefore, the score of Emma is 15.
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19- Choice D is correct
The correct answer is \frac{17}{18} If 17 balls are removed from the bag at random, there will be one ball in the bag. The probability of choosing a brown ball is 1 out of 18. Therefore, the probability of not choosing a brown ball is 17 out of 18 and the probability of having not a brown ball after removing 17 balls is the same.
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20- Choice C is correct
The correct answer is 7.32 The weight of 12.2 meters of this rope is: 12.2 \ × \ 600 g = 7320 g 1 kg = 1000 g, therefore, 7320 g ÷ \ 1000 = 7.32 kg
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21- Choice C is correct
The correct answer is 600 ml 4\% of the volume of the solution is alcohol. Let x be the volume of the solution. Then: 4\% of x = 24 ml ⇒ 0.04 \ x = 24 ⇒ x = 24 \ ÷ \ 0.04 = 600
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22- Choice C is correct
The correct answer is 400 Let x be the original price. If the price of a laptop is decreased by 10\% to $360, then: 90\% of x=360 ⇒ 0.90 \ x=360 ⇒ x=360 \ ÷ \ 0.90=400
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23- Choice B is correct
The correct answer is 9 Write the numbers in order: 4, \ 5, \ 8, \ 9, \ 13, \ 15, \ 18 Since we have 7 numbers (7 is odd), then the median is the number in the middle, which is 9.
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24- Choice A is correct
The correct answer is $300 Let L be the price of laptop and C be the price of computer. 3 \ (L) =5 \ (C) and L = $200 \ + \ C Therefore, 3 \ ($200 \ + \ C) =5 \ C ⇒ $600 \ + \ 3C = 5C ⇒ C=$300
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25- Choice C is correct
The correct answer is 97.6 Use the area of square formula. S = a^2 ⇒ 595.36 = a^2 ⇒ a = 24.4 One side of the square is 24.4 feet. Use the perimeter of square formula. P = 4 \ a ⇒ P = 4(24.4) ⇒ P = 97.6
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26- Choice C is correct
The correct answer is 6 hours The distance between Jason and Joe is 9 miles. Jason running at 5.5 miles per hour and Joe is running at the speed of 7 miles per hour. Therefore, every hour the distance is 1.5 miles less. 9 \ ÷ \ 1.5 = 6
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27- Choice D is correct
The correct answer is 80\% The failing rate is 11 out of 55 = \frac{11}{55} Change the fraction to percent: \frac{11}{55} \ × \ 100\%=20\% 20 percent of students failed. Therefore, 80 percent of students passed the exam.
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28- Choice C is correct
The correct answer is 60 Jason needs an 75\% average to pass for five exams. Therefore, the sum of 5 exams must be at least 5 \ × \ 75 = 375 The sum of 4 exams is: 68 \ + \ 72 \ + \ 85 \ + \ 90 = 315. The minimum score Jason can earn on his fifth and final test to pass is: 375 \ – \ 315 = 60
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29- Choice B is correct
The correct answer is 840 Use simple interest formula: I = prt (I = interest, p = principal, r = rate, t = time) I=(12000) \ (0.035) \ (2)=840
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30- Choice D is correct
The correct answer is 44 Let x be the integer. Then: 2 \ x \ – \ 5 = 83 Add 5 both sides: 2 \ x = 88 Divide both sides by 2: \ x = 44
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31- Choice B is correct
The correct answer is (- \ 1, \ 3) Input the points instead of x and y in the formula. Only option B works in the equation. 4 \ x \ + \ 6 \ y=14 4 \ (– \ 1) \ + \ 6 \ (3) =14
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32- Choice C is correct
The correct answer is 90 To find the number of possible outfit combinations, multiply number of options for each factor: 6 \ × \ 3 \ ×\ 5 = 90
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33- Choice B is correct
The correct answer is 30 The sum of supplement angles is 180. Let x be that angle. Therefore, x \ + \ 5 \ x = 180 6 \ x = 180, divide both sides by 6: \ x = 30
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34- Choice C is correct
The correct answer is 5 : 9 The average speed of John is: 150 \ ÷ \ 6 = 25 km The average speed of Alice is: 180 \ ÷ \ 4 = 45 km Write the ratio and simplify. 25: 45 ⇒ 5: 9
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35- Choice C is correct
The correct answer is 210 Let x be the number of soft drinks for 252 guests. It’s needed to have a proportional ratio to find x. \frac{10 \ soft \ drinks}{12 \ guests} = \frac{x}{252 \ guests} x = \frac{252 \ × \ 10}{12 }⇒x=210
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36- Choice B is correct
The correct answer is $23.8 Let x be the number of cans. Write a proportion and solve for x. \frac{5 \ cans}{$3.40) }= \frac{35 \ cans}{x} x =\frac{3.40\ × \ 35}{5} ⇒x=$23.8
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37- Choice B is correct
The correct answer is 5 x\% of 24 is 1.2, then: x\% 24 =1.2 ⇒ 0.24 \ x=1.2 ⇒ x=1.2 \ ÷ \ 0.24=5
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38- Choice C is correct
The correct answer is Mathematics Compare each score: In Algebra Joe scored 20 out of 25 in Algebra that it means 80\% of total mark. \frac{20}{25} = \frac{x}{100} ⇒x= 80 Joe scored 30 out of 40 in science that it means 75\% of total mark. \frac{30}{40} = \frac{x}{100} ⇒x= 75 Joe scored 68 out of 80 in mathematic that it means 85\% of total mark. \frac{68}{80} = \frac{x}{100} ⇒x= 85 Therefore, his score in mathematic is higher than his other scores.
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39- Choice C is correct
The correct answer is 480 m^3 Use the volume of square pyramid formula. V= \frac{1}{3} \ a^2 \ h ⇒ V= \frac{1}{3} \ (12 m)^2 \ × \ 10 m ⇒ V= 480 m^3
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39- Choice C is correct
The correct answer is 480 m^3 Use the volume of square pyramid formula. V= \frac{1}{3} \ a^2 \ h ⇒ V= \frac{1}{3} \ (12 m)^2 \ × \ 10 m ⇒ V= 480 m^3
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