Which numeric system was a base 20 system?
- A. Mayan
- B. Babylonian
- C. Roman
- D. Arabic
Correct Answer: A
Rationale: The Mayan numeric system was a base 20 system, known as vigesimal, as it used base 20 numerals. This system was unique and employed a combination of symbols and positional notation to represent numbers. The Babylonian system was a base 60 system, Roman numerals were based on combinations of letters, and Arabic numerals are in base 10, making choices B, C, and D incorrect.
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Multiply: 2 5 =
- A. 0.013
- B. 0.13
- C. 1.3
- D. 10
Correct Answer: D
Rationale: When you multiply 2 by 5, the result is 10, not 13. Therefore, the correct answer is 10, which is option D. Choices A, B, and C are incorrect because they do not represent the correct product of multiplying 2 by 5.
Express the ratio of 6:7 as a percentage.
- A. 67%
- B. 76%
- C. 86%
- D. 93%
Correct Answer: A
Rationale: To express the ratio 6:7 as a percentage, we first need to find the total parts in the ratio, which is 6 + 7 = 13. To convert this ratio to a percentage, divide the part you want to find the percentage for by the total parts, then multiply by 100. In this case, to find the percentage for 6 in the ratio 6:7, the calculation would be (6/13) * 100 = 46.15%. Therefore, the correct answer is A, 67%. Choices B, C, and D are incorrect percentages as they do not result from the correct calculation for the given ratio.
A patient's oxygen flow rate is set at 4 liters per minute. How many cubic centimeters of oxygen are delivered per minute?
- A. 400 cubic centimeters
- B. 4,000 cubic centimeters
- C. 40,000 cubic centimeters
- D. 400,000 cubic centimeters
Correct Answer: B
Rationale: 1 liter is equal to 1,000 cubic centimeters. Therefore, when the oxygen flow rate is 4 liters per minute, the calculation is 4 x 1,000 = 4,000 cubic centimeters. Hence, at a flow rate of 4 liters per minute, 4,000 cubic centimeters of oxygen are delivered per minute. Choice A, 400 cubic centimeters, is incorrect because it miscalculates the conversion from liters to cubic centimeters. Choices C and D, 40,000 cubic centimeters and 400,000 cubic centimeters, respectively, are significantly higher than the correct answer due to incorrect conversions or additional errors in calculation.
A child's toy block is a cube with side lengths of 5cm. What is its total surface area?
- A. 25 sq cm
- B. 50 sq cm
- C. 125 sq cm
- D. 150 sq cm
Correct Answer: D
Rationale: The surface area of a cube is calculated using the formula: 6 * (side length)^2. Substituting the side length of 5cm into the formula, we get: 6 * (5cm)^2 = 6 * 25cm^2 = 150 sq cm. Therefore, the total surface area of the toy block is 150 sq cm. Choices A (25 sq cm), B (50 sq cm), and C (125 sq cm) are incorrect as they do not correctly calculate the total surface area of the cube.
Bai Lin estimates that of her monthly paycheck, she puts 10% in savings and spends 30% on living expenses. If she has $1,545 left after that, how much is her monthly paycheck?
- A. $2,175
- B. $2,250
- C. $2,575
- D. $2,650
Correct Answer: C
Rationale: Let X be Bai Lin's monthly paycheck. From the given information, she puts 10% of X in savings and spends 30% on living expenses. This means she retains 60% (100% - 10% - 30%) of her paycheck, which equals $1,545. Therefore, 60% of X is $1,545. To find X, we divide $1,545 by 60% (or 0.60), which gives us X = $2,575. Hence, Bai Lin's monthly paycheck is $2,575. Therefore, the correct answer is $2,575. Choices A, B, and D are incorrect because they do not match the calculated monthly paycheck based on the given percentages and remaining amount.