Nokea
Solve for x: 3x + 9 = 0.
- A. x = -3
- B. x = -3
- C. x = 1
- D. x = 0
Correct Answer: B
Rationale: To solve the equation 3x + 9 = 0, first, isolate the variable x. Subtract 9 from both sides to get 3x = -9. Then, divide by 3 to solve for x, giving x = -3. Therefore, the correct answer is B. Choice A, x = -3, is the correct solution. Choices C and D are incorrect as they do not satisfy the equation when substituted back into it.
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Convert 2/5 to a decimal.
- A. 0.5
- B. 0.25
- C. 0.4
- D. 0.5
Correct Answer: C
Rationale: To convert 2/5 to a decimal, you divide the numerator (2) by the denominator (5): 2 · 5 = 0.4. Therefore, the correct decimal representation of 2/5 is 0.4. Choice A (0.5) is incorrect because it represents 1/2, not 2/5. Choice B (0.25) is incorrect as it represents 1/4, not 2/5. Choice D (0.5) is incorrect as it also represents 1/2, not 2/5.
A decorative box has a rectangular base (20cm by 15cm) and a hemispherical top with the same diameter as the base. What is the total surface area of the box (excluding the base)?
- A. 825 sq cm
- B. 1075 sq cm
- C. 1325 sq cm
- D. 1575 sq cm
Correct Answer: C
Rationale: To find the total surface area of the box excluding the base, calculate the lateral surface area of the rectangular base and the surface area of the hemisphere. The lateral surface area of the rectangular base is 2(20cm x 15cm) = 600 sq cm. The surface area of the hemisphere is 2πr^2, where r is half the diameter of the base, so r = 10cm. Thus, the surface area of the hemisphere is 2π(10cm)^2 = 200π sq cm ≈ 628.32 sq cm. Add the lateral surface area of the base and the surface area of the hemisphere: 600 sq cm + 628.32 sq cm ≈ 1228.32 sq cm. Therefore, the total surface area of the box is approximately 1228.32 sq cm, which is closest to 1325 sq cm (Choice C). Choices A, B, and D are incorrect as they do not represent the accurate calculation of the total surface area of the box.
What is the probability of rolling a 3 on a six-sided die?
- A. 1/6
- B. 1/4
- C. 1/3
- D. 1/2
Correct Answer: A
Rationale: The probability of rolling a specific number on a six-sided die is calculated by dividing the favorable outcomes (rolling a 3) by the total possible outcomes. In this case, there is 1 favorable outcome (rolling a 3) out of 6 total possible outcomes (numbers 1 to 6 on the die). Therefore, the probability of rolling a 3 is 1/6. Choice B (1/4), C (1/3), and D (1/2) are incorrect because they do not represent the correct calculation of the probability for rolling a 3 on a six-sided die.
How many milliliters are in 5 liters?
- A. 5000 milliliters
- B. 50 milliliters
- C. 500 milliliters
- D. 0.5 milliliters
Correct Answer: A
Rationale: To convert liters to milliliters, remember there are 1,000 milliliters in a liter. So, to find how many milliliters are in 5 liters, you multiply 5 (liters) by 1,000 (milliliters per liter), which equals 5,000 milliliters. Choice A is correct as it converts 5 liters to milliliters accurately. Choice B, 50 milliliters, is incorrect as it mistakenly converts liters to milliliters by a factor of 100 instead of 1,000. Choice C, 500 milliliters, is incorrect as it also wrongly converts liters to milliliters by a factor of 10 instead of 1,000. Choice D, 0.5 milliliters, is incorrect as it inaccurately converts 5 liters to 0.5 milliliters, which is not correct.
How many inches are in 3.5 yards?
- A. 126 inches
- B. 144 inches
- C. 132 inches
- D. 120 inches
Correct Answer: A
Rationale: To convert yards to inches, we use the conversion factor that 1 yard is equal to 36 inches. Therefore, 3.5 yards is equal to 3.5 multiplied by 36, which equals 126 inches. The correct answer is 126 inches. Choices B (144 inches), C (132 inches), and D (120 inches) are incorrect because they do not correctly calculate the conversion from yards to inches using the conversion factor of 1 yard equals 36 inches.