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What is the solution to 4 x 7 + (25 - 21)²?
- A. 512
- B. 36
- C. 44
- D. 22
Correct Answer: C
Rationale: To find the solution, first solve the expression inside the parentheses: 25 - 21 = 4. Then, square the result from the parentheses: 4² = 16. Next, perform the multiplication: 4 x 7 = 28. Finally, add the results: 28 + 16 = 44. Therefore, the correct answer is 44. Choice A (512), Choice B (36), and Choice D (22) are incorrect as they do not follow the correct order of operations for solving the given mathematical expression.
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What is the overall median of Dwayne's current scores: 78, 92, 83, 97?
- A. 19
- B. 85
- C. 83
- D. 87.5
Correct Answer: B
Rationale: To find the median of a set of numbers, first arrange the scores in ascending order: 78, 83, 92, 97. Since there is an even number of scores, we find the median by taking the average of the two middle values. In this case, the middle values are 83 and 92. Calculating (83 + 92) / 2 = 85, we determine that the overall median of Dwayne's scores is 85. Choice A (19) is incorrect as it does not correspond to any value in the given set of scores. Choice C (83) is the median of the original set but not the overall median once arranged. Choice D (87.5) is the average of all scores but not the median.
You measure the width of your door to be 36 inches. The true width of the door is 75 inches. What is the relative error in your measurement?
- A. 0.52%
- B. 0.01%
- C. 0.99%
- D. 0.10%
Correct Answer: A
Rationale: The relative error is calculated using the formula: (|Measured Value - True Value| / True Value) * 100%. Substituting the values given, we have (|36 - 75| / 75) * 100% = (39 / 75) * 100% ≈ 0.52 * 100% = 0.52%. Therefore, the relative error in measurement is approximately 0.52%. Choice A is correct because it reflects this calculation. Choice B is incorrect as it represents a lower relative error than the actual value obtained. Choice C is incorrect as it overestimates the relative error. Choice D is incorrect as it underestimates the relative error.
Kimberley earns $10 an hour babysitting, and after 10 p.m., she earns $12 an hour, with the amount paid being rounded to the nearest hour accordingly. On her last job, she worked from 5:30 p.m. to 11 p.m. In total, how much did Kimberley earn on her last job?
- A. $45
- B. $57
- C. $62
- D. $42
Correct Answer: C
Rationale: Kimberley worked from 5:30 p.m. to 11 p.m., which is a total of 5.5 hours before 10 p.m. (from 5:30 p.m. to 10 p.m.) and 1 hour after 10 p.m. The earnings she made before 10 p.m. at $10 an hour was 5.5 hours * $10 = $55. Her earnings after 10 p.m. for the rounded hour were 1 hour * $12 = $12. Therefore, her total earnings for the last job were $55 + $12 = $67. Since the amount is rounded to the nearest hour, the closest rounded amount is $62. Therefore, Kimberley earned $62 on her last job. Choice A is incorrect as it does not consider the additional earnings after 10 p.m. Choices B and D are incorrect as they do not factor in the hourly rates and the total hours worked accurately.
Adrian measures the circumference of a circular picture frame with a radius of 3 inches. Which of the following is the best estimate for the circumference of the frame?
- A. 12 inches
- B. 16 inches
- C. 18 inches
- D. 24 inches
Correct Answer: C
Rationale: To calculate the circumference of a circle, use the formula 2πr, where r is the radius. In this case, with a radius of 3 inches, the estimated circumference would be 2 x π x 3 = 6π ≈ 18.85 inches. Therefore, the best estimate for the circumference of the frame is 18 inches (Choice C). Choice A (12 inches) is too small as it corresponds to the diameter rather than the circumference. Choice B (16 inches) and Choice D (24 inches) are also incorrect as they do not reflect the accurate calculation based on the given radius.
67 miles is equivalent to how many kilometers to three significant digits?
- A. 107 km
- B. 106 km
- C. 33 km
- D. 85 km
Correct Answer: A
Rationale: To convert miles to kilometers, the conversion factor is 1 mile ≈ 1.609 kilometers. Therefore, to convert 67 miles to kilometers, you would multiply: 67 miles 1.609 km/mile = 107.703 km. When rounded to three significant digits, this gives 108 km. Therefore, 67 miles is approximately 108 kilometers. Choice A is correct because it is the closest rounded value to three significant digits. Choices B, C, and D are incorrect as they do not match the calculated conversion of 108 km.