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If a tree grows an average of 4.2 inches in a day, what is the rate of change in its height per month? Assume a month is 30 days.
- A. 0.14 inches per month
- B. 4.2 inches per month
- C. 34.2 inches per month
- D. 126 inches per month
Correct Answer: D
Rationale: The tree grows at an average rate of 4.2 inches per day. To find the rate of change per month, multiply the daily growth rate by the number of days in a month (30 days):
4.2 inches/day 30 days = 126 inches per month.
Therefore, the rate of change in the tree's height is 126 inches per month, making option D the correct answer. Option A is incorrect because it miscalculates the rate based on daily growth. Option B is incorrect as it doesn't account for the total days in a month. Option C is incorrect as it overestimates the monthly growth rate.
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A piece of wood that is 7 1/2 feet long has 3 1/4 feet cut off. How many feet of wood remain?
- A. 4 1/4 feet
- B. 4 1/2 feet
- C. 3 1/2 feet
- D. 3 3/4 feet
Correct Answer: A
Rationale: To find the remaining length of wood, you need to subtract 3 1/4 feet from 7 1/2 feet. When you subtract the fractions, 7 1/2 - 3 1/4, you get 15/2 - 13/4 = 30/4 - 13/4 = 17/4 = 4 1/4 feet. Therefore, the correct answer is 4 1/4 feet. Choice B (4 1/2 feet) is incorrect because the subtraction result is not 1/2. Choice C (3 1/2 feet) is incorrect as it does not match the correct result of 4 1/4 feet. Choice D (3 3/4 feet) is also incorrect as it does not align with the correct answer obtained from the subtraction of fractions.
Given that three vertices of a parallelogram are (1, 2), (3, 4), and (5, 6), what are the coordinates of the fourth vertex?
- A. (1, 6)
- B. (3, 2)
- C. (5, 2)
- D. (7, 8)
Correct Answer: D
Rationale: To find the fourth vertex of a parallelogram, we can use the properties of a parallelogram. Opposite sides of a parallelogram are parallel and equal in length. Therefore, we can determine the fourth vertex by extending the line formed by the first two points. If we extend the line from (1, 2) to (3, 4), we find that it has a slope of 1. This means that extending the line from (3, 4) by the same slope will give us the fourth vertex. By adding 2 units to both x and y coordinates of (5, 6), we get (7, 8) as the coordinates of the fourth vertex. Therefore, the correct answer is (7, 8). Choices A, B, and C are incorrect as they do not satisfy the properties of a parallelogram and the given coordinate points.
Solve |x| = 10.
- A. -10, 10
- B. -11, 11
- C. -12, 12
- D. -13, 13
Correct Answer: A
Rationale: The absolute value of x is equal to 10 when x is either -10 or 10. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not satisfy the equation |x| = 10. For choice B, -11 and 11 do not satisfy the condition. Choices C and D also do not provide solutions that meet the equation's requirement.
Simplify the expression: 2x + 3x - 5.
- A. 5x - 5
- B. 5x
- C. x - 5
- D. 2x - 5
Correct Answer: A
Rationale: To simplify the expression 2x + 3x - 5, follow these steps: Identify and combine like terms. The terms 2x and 3x are both 'like terms' because they both contain the variable x. Add the coefficients of the like terms: 2x + 3x = 5x. Simplify the expression. After combining the like terms, the expression becomes 5x - 5, which includes the simplified term 5x and the constant -5. Thus, the fully simplified expression is 5x - 5, making Option A the correct answer. This method ensures all terms are correctly simplified by combining similar elements and retaining constants.
What is the product of 2/3 and 3/4?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: A
Rationale: To multiply fractions, you multiply the numerators to get the new numerator and multiply the denominators to get the new denominator. Therefore, multiplying 2/3 by 3/4 results in (2*3) / (3*4) = 6/12. Simplifying 6/12 by dividing both the numerator and denominator by 6 gives 1. Hence, the correct answer is 1. Choices B, C, and D are incorrect as they do not represent the correct product of multiplying 2/3 by 3/4.