A water fountain has a spherical base with a diameter of 50cm and a cylindrical body with a diameter of 30cm and a height of 80cm. What is the total surface area of the fountain (excluding the water surface)?

Correct Answer: C

Rationale: To find the total surface area of the fountain, we first calculate the surface area of the sphere and the cylinder separately. For the sphere: - Radius = Diameter / 2 = 50 / 2 = 25 cm - Surface area of a sphere = 4πr² = 4 x π x 25² = 500π cm² For the cylinder: - Radius = Diameter / 2 = 30 / 2 = 15 cm - Surface area of a cylinder = 2πrh + 2πr² = 2 x π x 15 x 80 + 2 x π x 15² = 240π + 450π = 690π cm² Total surface area = Surface area of sphere + Surface area of cylinder = 500π + 690π = 1190π cm² ≈ 5486 sq cm. Therefore, the correct answer is C. Choice A (3142 sq cm) is incorrect as it is much smaller than the correct answer. Choices B and D are also incorrect as they do not reflect the accurate calculation of the total surface area of the fountain.

Correct Answer: C

Rationale: The greatest common factor (GCF) of two numbers is the largest number that divides both numbers without leaving a remainder. To find the GCF of 12 and 18, we factorize each number: 12 = 2 x 2 x 3 and 18 = 2 x 3 x 3. The common factors are 2 and 3. The GCF is the product of these common factors, which is 6. Therefore, 6 is the greatest common factor of 12 and 18. Choice A (2) and Choice B (3) are factors of both numbers but not the greatest common factor. Choice D (9) is not a factor of both 12 and 18, making it incorrect.

Correct Answer: D

Rationale: To convert 5 3/4 to a decimal, divide the numerator (3) by the denominator (4) to get 0.75. Adding this to the whole number 5 results in 5.75. When rounding to the nearest tenth, 5.75 rounds to 5.8. Choice A, 5.75, is the exact conversion before rounding, so it is incorrect. Choice B, 5.7, is incorrect because it does not account for the 0.05 difference when rounding. Choice C, 6, is incorrect as it is the closest whole number but not a decimal approximation. Therefore, the correct answer is 5.8.

Correct Answer: B

Rationale: Given x=11, substitute into the expression: (11 + 44) / (2*11) = 55 / 22 = 2.5. Therefore, the correct answer is 2.5. Choice A (33) is incorrect as it does not represent the correct calculation. Choice C (13) is incorrect as it is not the result of the expression. Choice D (55/22) is incorrect as it is the same as the simplified form of the expression, not the answer to the calculation.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.