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.

Correct Answer: B

Rationale: To convert military time to regular time, subtract 12 from the hours if the time is in the afternoon or evening. In this case, 21 - 12 = 9, so 2120 hours is equivalent to 9:20 P.M. Therefore, the correct answer is option B, 9:20 P.M. Choices A, C, and D are incorrect because they do not correctly adjust the military time to regular time format. Choice A shows 9:20 A.M., which is incorrect as the time is in the evening. Choices C and D show times that are not derived from the given military time, making them incorrect as well.

Correct Answer: B

Rationale: Rationale: - Relatively prime numbers are numbers that share no common factors other than 1. - To determine if two numbers are relatively prime, we need to find the greatest common divisor (GCD) of the two numbers. If the GCD is 1, then the numbers are relatively prime. - Let's calculate the GCD for each pair of numbers: A) GCD(12, 16) = 4, not relatively prime B) GCD(15, 17) = 1, relatively prime C) GCD(20, 24) = 4, not relatively prime D) GCD(28, 36) = 4, not relatively prime Therefore, the pair of numbers 15 and 17 are relatively prime because their greatest common divisor is 1, meaning they share no common factors other than 1.

Correct Answer: A

Rationale: To find the volume of a pyramid, you can use the formula: Volume = (1/3) * base area * height. In this case, the base area is the square of side length 20 meters, which is 20 * 20 = 400 square meters. The original height of the pyramid is 30 meters. Therefore, the volume of the pyramid in its original state is (1/3) * 400 * 30 = 12000 cubic meters. Choice A is correct. Choices B, C, and D are incorrect as they do not correctly calculate the volume using the original height and base area of the pyramid.

Correct Answer: C

Rationale: Since Bruno has 27 stamps from Europe, which is 15 more than from Africa, he must have 27 - 15 = 12 stamps from Africa. Since he also has 18 more stamps from Asia than from Africa, he must have 12 + 18 = 30 stamps from Asia. Therefore, Bruno has 30 Asian stamps. Choice A (12) is the number of stamps Bruno has from Africa, not Asia. Choices B (22) and D (40) are not derived from the correct calculations based on the given information.