Nokea
Which of the following describes a proportional relationship?
- A. Johnathan opens a savings account with an initial deposit of $150 and deposits $125 per month
- B. Bruce pays his employees $12 per hour worked during the month of December, as well as a $250 bonus
- C. Alvin pays $28 per month for his phone service plus $0.07 for each long-distance minute used
- D. Kevin drives 65 miles per hour
Correct Answer: A
Rationale: A proportional relationship is one in which two quantities vary directly with each other. In choice A, the amount deposited per month is directly proportional to the initial deposit. The relationship can be represented as y = 125x + 150, where x is the number of months and y is the total amount in the account. Choices B and C involve additional fixed amounts or variable costs that do not maintain a constant ratio, making them non-proportional relationships. Choice D refers to a constant speed of driving, which is not a proportional relationship as it does not involve varying quantities that change in direct proportion.
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A rectangular solid box has a square base with a side length of 5 feet and a height of h feet. If the volume of the box is 200 cubic feet, which of the following equations can be used to find h?
- A. 5h = 200
- B. 5h² = 200
- C. 25h = 200
- D. h = 200 · 5
Correct Answer: C
Rationale: The volume formula for a rectangular solid is V = l w h. In this case, the length and width are both 5 feet. Substituting the values into the formula gives V = 5 5 h = 25h = 200. Therefore, h = 200 · 25 = 8. Option A is incorrect because the product of length, width, and height is not directly equal to the volume. Option B is incorrect as squaring the height is not part of the volume formula. Option D is incorrect as it oversimplifies the relationship between height and volume, not considering the base dimensions.
Which of the following is listed in order from least to greatest?
- A. -2 3/4, -2 7/8, -1/5, 2/5, 1/8
- B. -1/5, 1/8, 2/5, -2 3/4, -2 7/8
- C. -2 7/8, -2 3/4, -1/5, 1/8, 2/5
- D. 1/8, 2/5, -1/5, -2 7/8, -2 3/4
Correct Answer: C
Rationale: To determine the order from least to greatest, we can convert all fractions and mixed numbers to decimals or use a least common denominator. Converting the fractions in Choice C to decimals, we get -2.875, -2.75, -0.2, 0.125, and 0.4 when reading from left to right. Negative integers with larger absolute values are less than negative integers with smaller absolute values. Therefore, the correct answer is Choice C. Choices A, B, and D are incorrect because they do not present the numbers in the correct order from least to greatest when converted to decimals or compared using common denominators.
Which of the following is listed in order from least to greatest? (-3/4, -7 4/5, -8, 18%, 0.25, 2.5)
- A. -3/4, -7 4/5, -8, 18%, 0.25, 2.5
- B. -8, -7 4/5, -3/4, 18%, 0.25, 2.5
- C. 18%, 0.25, -3/4, 2.5, -7 4/5, -8
- D. -8, -7 4/5, -3/4, 18%, 0.25, 2.5
Correct Answer: D
Rationale: To arrange the numbers from least to greatest, we first compare the integers, then the fractions, and finally the percentages and decimals. The correct order is -8, -7 4/5, -3/4, 18%, 0.25, 2.5. Choice A is incorrect because it incorrectly orders the fractions. Choice B is incorrect because it incorrectly places -8 after the fractions. Choice C is incorrect because it starts with the percentages instead of the integers, leading to an incorrect order.
Jeremy put a heavy chalk mark on the tire of his bicycle. His bike tire is 27 inches in diameter. When he rolled the bike, the chalk left marks on the sidewalk. Which expression can be used to best determine the distance, in inches, the bike rolled from the first mark to the fourth mark?
- A. 3(27π)
- B. 4π(27)
- C. (27 · 3)π
- D. (27 · 4)π
Correct Answer: A
Rationale: The distance traveled by the bike in one complete roll of the tire is equal to the circumference, which can be calculated using the formula C = πd, where d is the diameter. Given that the diameter of the bike tire is 27 inches, the circumference is obtained by multiplying the diameter by π. As the tire rolls from the first mark to the fourth mark, it completes three full rotations (one complete roll plus two more). Therefore, the total distance rolled is 3 times the circumference, which results in 3(27π). Choice A is correct. Choice B is incorrect as it incorrectly multiplies the diameter by 4π instead of multiplying the circumference by 4. Choices C and D are incorrect as they involve dividing the diameter by a number, which is not applicable in this context.
What is the surface area of the cylinder shown below?
- A. 602.9 cm²
- B. 904.3 cm²
- C. 1,408.7 cm²
- D. 1,507.2 cm²
Correct Answer: D
Rationale: The surface area of a cylinder can be calculated using the formula: S = 2πr² + 2πrh, where r is the radius and h is the height. Substituting the values for radius (12) and height (8) into the formula: S = 2π(12)² + 2π(12)(8). S = 2π(144) + 2π(96). S = 288π + 192π. S = 480π ≈ 1507.964. Therefore, the surface area of the cylinder is approximately 1507.2 square centimeters. Choice A, 602.9 cm², is incorrect as it is significantly lower than the correct value. Choice B, 904.3 cm², is also incorrect as it does not match the calculated surface area. Choice C, 1,408.7 cm², is incorrect as it does not align with the calculated value of the surface area.