Nokea
Which of the following is NOT a way to write 40 percent of N?
- A. 0.4N
- B. N/40
- C. 2/5 N
- D. 40N/100
Correct Answer: B
Rationale: The correct answer is B: N/40. To find 40% of N, you multiply N by 0.4, so 0.4N is the correct representation. Choice B, N/40, is incorrect because dividing N by 40 does not give you 40% of N. Choice C, 2/5 N, is equivalent to 40% of N since 2/5 is the same as 40% when simplified. Choice D, 40N/100, is also correct since 40% can be represented as 40/100, which simplifies to 0.4, making 40N/100 another valid way to write 40% of N.
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What is the volume of a cube with a side length of 3 cm?
- A. 9 cm³
- B. 27 cm³
- C. 18 cm³
- D. 12 cm³
Correct Answer: B
Rationale: To find the volume of a cube, you cube the length of one side. In this case, the side length is 3 cm, so the volume is calculated as 3 cm * 3 cm * 3 cm = 27 cm³. Therefore, the correct answer is 27 cm³. Choice A (9 cm³), Choice C (18 cm³), and Choice D (12 cm³) are incorrect as they do not correctly calculate the volume of a cube with a side length of 3 cm.
What number is 20 equal to 40% of?
- A. 50
- B. 8
- C. 200
- D. 5000
Correct Answer: A
Rationale: To find the number that 20 is equal to 40% of, you can set up the equation: 20 = 0.4 * x, where x is the unknown number. To solve for x, divide both sides of the equation by 0.4. This gives x = 20 / 0.4 = 50. Therefore, 20 is 40% of 50.
Choice B, 8, is incorrect because 20 is not equal to 40% of 8. Choice C, 200, is incorrect because 20 is not equal to 40% of 200. Choice D, 5000, is incorrect because 20 is not equal to 40% of 5000. The correct answer is 50.
What is the area of a rectangle with a length of 5 cm and a width of 4 cm?
- A. 9 cm²
- B. 20 cm²
- C. 10 cm²
- D. 25 cm²
Correct Answer: B
Rationale: To find the area of a rectangle, you multiply its length by its width. In this case, the length is 5 cm and the width is 4 cm. So, Area = length * width = 5 cm * 4 cm = 20 cm². Therefore, the correct answer is 20 cm². Choice A (9 cm²), Choice C (10 cm²), and Choice D (25 cm²) are incorrect as they do not result from the correct calculation of multiplying the length and width of the rectangle.
What is the perimeter of a rectangle with a length of 7 cm and a width of 3 cm?
- A. 21 cm
- B. 10 cm
- C. 14 cm
- D. 20 cm
Correct Answer: D
Rationale: To find the perimeter of a rectangle, you add the lengths of all its sides. In this case, the formula for the perimeter of a rectangle is 2*(length + width). Substituting the given values, we get: 2*(7 cm + 3 cm) = 2*(10 cm) = 20 cm. Therefore, the correct answer is 20 cm. Choice A (21 cm) is incorrect because it is the sum of the individual sides rather than the perimeter. Choice B (10 cm) is incorrect because it only represents one side of the rectangle. Choice C (14 cm) is incorrect as it is not the total perimeter of the rectangle.
How is the number -4 classified?
- A. Real, rational, integer, whole, natural
- B. Real, rational, integer, natural
- C. Real, rational, integer
- D. Real, irrational
Correct Answer: C
Rationale: The number -4 is classified as a real number because it exists on the number line. It is also a rational number since it can be expressed as -4/1. Additionally, -4 is an integer because it is a whole number that can be positive, negative, or zero. However, -4 is not a whole number because whole numbers are non-negative integers starting from zero. Similarly, -4 is not a natural number since natural numbers are positive integers starting from one. Therefore, the correct classification for the number -4 is real, rational, and integer, making option C the correct answer.