Correct Answer: A

Rationale: An integer is a whole number that can be positive, negative, or zero. It does not include fractions or decimals. Choice B, 'A number with a decimal point,' is incorrect because integers do not have decimal points. Choice C, 'A fraction,' is incorrect because integers are not expressed as ratios of two integers. Choice D, 'A percentage,' is incorrect because integers are not necessarily related to proportions out of 100.

Correct Answer: A

Rationale: Rational numbers are those that can be written as a simple fraction, including whole numbers and decimals that either terminate or repeat. Irrational numbers, on the other hand, cannot be expressed as fractions. Choice B is incorrect because not all rational numbers necessarily terminate or repeat. Choice C is incorrect as it oversimplifies the concept of rational and irrational numbers by only considering whole numbers and decimals. Choice D is incorrect as it inaccurately defines rational and irrational numbers solely based on decimals terminating or repeating, excluding the broader category of fractions.

Correct Answer: D

Rationale: To calculate a 30% increase from the current dosage of 270 mg, first find 30% of 270, which is 81 mg. Add this 81 mg increase to the original dosage of 270 mg to get the new dosage, which is 351 mg (270 mg + 81 mg = 351 mg). Therefore, the correct answer is 351 mg. Choice A (81 mg) is incorrect because this value represents only the calculated 30% increase, not the total dosage after the increase. Choice B (270 mg) is the original dosage and does not account for the 30% increase. Choice C (300 mg) is close to the correct answer but does not consider the precise 30% increase calculation, leading to an incorrect total dosage.

Correct Answer: D

Rationale: The correct answer is D: 17.8 cm. To convert inches to centimeters, you can use the conversion factor 1 inch = 2.54 cm. Therefore, 7 inches is equal to 7 * 2.54 = 17.78 cm, which rounds to 17.8 cm. Choices A, B, and C are incorrect because they do not correspond to the correct conversion of 7 inches to centimeters.

Correct Answer: B

Rationale: To determine the greatest value among the choices, you need to convert all options to a common format. In this case, converting fractions to decimals will help compare them. When 7 · 5 is calculated, it equals 1.4, which is greater than 0.729 (choice C) and 0.78 (choice A when rounded). The percentage 73% (choice D) is equivalent to 0.73, making 7 · 5 the largest value. Therefore, the correct answer is B. Choice A is smaller than B, as 43 · 55 equals approximately 0.78. Choice C is smaller than B, as 0.729 is less than 1.4. Choice D is smaller than B, as 73% is equal to 0.73, which is less than 1.4.