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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: The circumference of a circle is given by the formula Circumference = 2 x π x radius. Given that the radius of the picture frame is 3 inches, the estimated circumference can be calculated as 2 x π x 3 = 18.84 inches, which is closest to 18 inches among the given options. Choice A (12 inches) is too small, choice B (16 inches) is also underestimated, and choice D (24 inches) is too large based on the calculated value using the formula.
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What is the volume of a ball with a diameter of 7 inches?
- A. 165.7 in³
- B. 179.6 in³
- C. 184.5 in³
- D. 192.3 in³
Correct Answer: A
Rationale: To find the volume of a sphere, the formula V = (4/3)πr³ is used, where r is the radius of the sphere. Given that the diameter of the ball is 7 inches, the radius (r) would be half of the diameter, which is 3.5 inches. Plugging this value into the formula: V = (4/3)π(3.5)³ = (4/3)π(42.875) ≈ 165.7 in³. Therefore, the correct answer is A. Choice B, C, and D are incorrect as they do not accurately represent the volume of the ball with a diameter of 7 inches.
A book has a width of 5 decimeters. What is the width of the book in centimeters?
- A. 0.25 centimeters
- B. 25 centimeters
- C. 250 centimeters
- D. 0.025 centimeters
Correct Answer: B
Rationale: To convert decimeters to centimeters, you need to multiply by 10 since 1 decimeter is equal to 10 centimeters. Therefore, to find the width of the book in centimeters, multiply 5 decimeters by 10: 5 decimeters * 10 = 50 centimeters. This means the width of the book is 50 centimeters, making choice B, "25 centimeters," the correct answer. Choices A, C, and D are incorrect because they do not correctly convert decimeters to centimeters.
Elijah drove 45 miles to his job in an hour and ten minutes in the morning. On the way home in the evening, however, the traffic was much heavier, and the same trip took an hour and a half. What was his average speed in miles per hour for the round trip?
- A. 30
- B. 45
- C. 36
- D. 40
Correct Answer: A
Rationale: To find the average speed for the round trip, we calculate the total distance and total time traveled. The total distance for the round trip is 45 miles each way, so 45 miles * 2 = 90 miles. The total time taken for the morning trip is 1 hour and 10 minutes (1.17 hours), and for the evening trip is 1.5 hours. Therefore, the total time for the round trip is 1.17 hours + 1.5 hours = 2.67 hours. To find the average speed, we divide the total distance by the total time: 90 miles / 2.67 hours ≈ 33.7 miles per hour. The closest option is A, 30 miles per hour, making it the correct answer. Choice B (45) is the total distance for the round trip, not the average speed. Choices C (36) and D (40) are not derived from the correct calculations and do not represent the average speed for the round trip.
Approximately by what percentage are there more female staff members in City Y compared to City X?
- A. 5%
- B. 10%
- C. 15%
- D. 20%
Correct Answer: D
Rationale: To find the percentage difference in female staff members between City Y and City X, you subtract the percentage of female staff members in City X from the percentage in City Y. So, 60% (City Y) - 40% (City X) = 20%. This means there are 20% more female staff members in City Y compared to City X. Choices A, B, and C are incorrect percentages and do not accurately represent the 20% difference between the two cities.
What is the simplest way to write the following expression? 5x - 2y + 4x + y
- A. 9x - y
- B. 9x - 3y
- C. 9x + 3y
- D. x; y
Correct Answer: A
Rationale: To simplify the given expression 5x - 2y + 4x + y, we combine like terms. Grouping the x terms together and the y terms together, we have 5x + 4x - 2y + y. Combining like terms results in 9x - y. Therefore, the simplest form of the expression is 9x - y, which corresponds to option A. Option B is incorrect because it incorrectly subtracts 3y instead of just y. Option C is incorrect because it adds 3y instead of subtracting y. Option D is incorrect as it separates x and y with a semicolon instead of an operation, providing no simplified expression.