Correct Answer: C

Rationale: To convert pounds to kilograms, you need to divide the weight in pounds by the conversion factor of 2.2 (1kg = 2.2lbs). 180 pounds / 2.2 = 81.82 kg Rounded to the nearest whole number, the weight of 180 pounds is approximately 82kg. Therefore, the correct answer is 82kg, which is option C. Option B (75kg) is not correct as it is significantly lower than the calculated value. Options A (68kg) and D (90kg) are also incorrect as they do not match the converted weight of 180 pounds.

Correct Answer: B

Rationale: Rationale: 1. Let x be the volume of the 10% solution needed and y be the volume of water needed. 2. The total volume of the final solution is 200ml, so x + y = 200. 3. The concentration of the final solution is 5%, so the amount of salt in the final solution is 0.05 * 200 = 10g. 4. The amount of salt in the 10% solution is 0.1x, and the amount of salt in the water is 0, so the total amount of salt in the final solution is 0.1x. 5. Since the total amount of salt in the final solution is 10g, we have 0.1x = 10. 6. Solving for x, we get x = 100ml. 7. Substituting x =

Correct Answer: B

Rationale: To convert military time to regular time, subtract 12 from the hours if the time is in the afternoon or evening. In this case, 21 - 12 = 9, so 2120 hours is equivalent to 9:20 P.M. Therefore, the correct answer is option B, 9:20 P.M. Choices A, C, and D are incorrect because they do not correctly adjust the military time to regular time format. Choice A shows 9:20 A.M., which is incorrect as the time is in the evening. Choices C and D show times that are not derived from the given military time, making them incorrect as well.

Correct Answer: C

Rationale: To convert pounds to kilograms, you need to divide the weight in pounds by the conversion factor of 2.2 (1kg = 2.2lbs). 180 pounds / 2.2 = 81.82 kg Rounded to the nearest whole number, the weight of 180 pounds is approximately 82kg. Therefore, the correct answer is 82kg, which is option C. Option B (75kg) is not correct as it is significantly lower than the calculated value. Options A (68kg) and D (90kg) are also incorrect as they do not match the converted weight of 180 pounds.

Correct Answer: D

Rationale: The surface area of a cube is calculated using the formula: 6 * (side length)^2. Substituting the side length of 5cm into the formula, we get: 6 * (5cm)^2 = 6 * 25cm^2 = 150 sq cm. Therefore, the total surface area of the toy block is 150 sq cm. Choices A (25 sq cm), B (50 sq cm), and C (125 sq cm) are incorrect as they do not correctly calculate the total surface area of the cube.