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A cell has a diameter of 0.1 meter, and another cell has a diameter of 0.05 meters. How many times larger is the first cell compared to the second cell?
- A. 2
- B. 4
- C. 8
- D. 16
Correct Answer: A
Rationale: To determine how many times larger the first cell is compared to the second cell, divide the diameter of the first cell by the diameter of the second cell: 0.1 / 0.05 = 2. Therefore, the first cell is 2 times larger than the second cell. Choice B, C, and D are incorrect because they do not provide the accurate calculation for the size difference between the two cells.
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Find the area in square centimeters of a circle with a diameter of 16 centimeters. Use 3.14 for π.
- A. 25.12
- B. 50.24
- C. 100.48
- D. 200.96
Correct Answer: D
Rationale: The formula for the area of a circle is: Area = π x (radius²). Given: Diameter = 16 cm, so Radius = Diameter / 2 = 16 / 2 = 8 cm. Now, calculate the area using π = 3.14: Area = 3.14 x (8²) = 3.14 x 64 = 200.96 cm². The correct answer is D (200.96 cm²) as it correctly calculates the area of the circle. Choices A, B, and C are incorrect as they do not represent the accurate area of the circle based on the given diameter and π value.
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 median of the data set: 3, 5, 7, 9, 11?
- A. 3
- B. 7
- C. 9
- D. 5
Correct Answer: B
Rationale: To find the median of a set of numbers, you arrange them in ascending order and then find the middle value. Given the data set 3, 5, 7, 9, 11, when arranged in ascending order, becomes 3, 5, 7, 9, 11. The middle value in this set is 7, making it the median. Choice A (3) is the smallest value, not the middle value. Choice C (9) and Choice D (5) are not the middle values of the set either. Therefore, the correct answer is B (7).
Eric buys 5 1/2 pounds of apples each week for four weeks. How many total pounds does he buy?
- A. 22 pounds
- B. 20 pounds
- C. 18 pounds
- D. 24 pounds
Correct Answer: A
Rationale: To find the total pounds of apples Eric buys, you need to multiply the pounds of apples bought each week (5 1/2 pounds) by the number of weeks (4 weeks). When you multiply 5 1/2 by 4, you get 22 pounds. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not accurately calculate the total pounds purchased over the four weeks.
Simplify (x^2 - y^2) / (x - y)
- A. x + y
- B. x - y
- C. 1
- D. (x + y)/(x - y)
Correct Answer: A
Rationale: The expression x^2 - y^2 is a difference of squares, which follows the identity: x^2 - y^2 = (x + y)(x - y). Therefore, the given expression becomes: (x^2 - y^2) / (x - y) = (x + y)(x - y) / (x - y). Since (x - y) appears in both the numerator and the denominator, they cancel each other out, leaving x + y. Thus, the simplified form of (x^2 - y^2) / (x - y) is x + y. Therefore, the correct answer is A (x + y). Option B (x - y) is incorrect as it does not result from simplifying the given expression. Option C (1) is incorrect as it does not account for the variables x and y present in the expression. Option D ((x + y)/(x - y)) is incorrect as it presents the simplified form in a different format than the correct answer.