Correct Answer: C

Rationale: 12 - 7 & 4\5 equals 4 & 1\5.

Correct Answer: A

Rationale: To convert centimeters to inches, divide the measurement in centimeters by 2.54 (since 1 inch = 2.54 cm). Therefore, 65.4 cm · 2.54 = 25.74 inches. This means that the model's waist measurement of 65.4 centimeters is equivalent to 25.74 inches. Choices B, C, and D are incorrect as they do not result from the correct conversion calculation.

Correct Answer: A

Rationale: To find the total number of patients monitored, add the patients monitored by each nurse: 6 (Nurse 1) + 8 (Nurse 2) + 12 (Nurse 3) = 26 patients. Therefore, the correct answer is 26 patients. Choice B (24 patients), Choice C (20 patients), and Choice D (23 patients) are incorrect as they do not correctly sum up the patients monitored by each nurse.

Correct Answer: C

Rationale: To find the volume of the frustum of a cone, divide it into two cones and calculate their volumes separately. The formula for the volume of a cone frustum involves the radii of both bases and the height. The volume of the frustum cone can be calculated as V = 1/3 * π * h * (R^2 + r^2 + R * r), where R is the larger radius, r is the smaller radius, and h is the height. Substituting the values, V = 1/3 * π * 15 * (10^2 + 20*10 + 20^2) = 1875 cu cm. Therefore, the correct answer is 1875 cu cm. Choice A, B, and D are incorrect as they do not correspond to the correct calculation of the frustum's volume.

Correct Answer: A

Rationale: To change a fraction into a ratio, you replace the fraction bar (/) with a colon (:). Therefore, 19/40 as a ratio is written as 19:40. Choice B (40:19) is incorrect as it reverses the order of the numbers. Choice C (19:4) is incorrect as it uses the denominator as the second number, which is not the correct way to represent a ratio. Choice D (40:4) is incorrect as it does not reflect the original fraction accurately.