Correct Answer: B

Rationale: The Hindu-Arabic numeral system consists of ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. These ten digits are used as the fundamental symbols to represent numbers in this numerical system. Choice A, 'Two,' is incorrect as there are more than two digits in the system. Choice C, 'Twelve,' is incorrect as it exceeds the total number of digits in the system. Choice D, 'Twenty,' is incorrect as it overestimates the number of digits present in the Hindu-Arabic numeral system.

Correct Answer: B

Rationale: To find the number that 80 is 125% of, we can set up the equation: x = 80 / 1.25. Solving this equation gives x = 64. Therefore, 80 is 125% of 64. Choice A (48) is incorrect because it is not the correct value that 80 is 125% of. Choice C (68) is incorrect as it is not the value that satisfies the given percentage relationship. Choice D (78) is incorrect as it does not match the calculation result.

Correct Answer: B

Rationale: Rationale: Given that 1 teaspoon is equal to 5ml, and the medication dosage is listed as 1/2 teaspoon, we need to find half of 5ml. 1/2 of 5ml = 5ml / 2 = 2.5ml Therefore, the equivalent dosage in milliliters for 1/2 teaspoon is 2.5ml.

Correct Answer: B

Rationale: To find the number that 6 is equal to 15% of, we set up the equation 0.15x = 6, where x is the unknown number. To solve for x, we divide 6 by 0.15, which gives us x = 40. Therefore, 6 is equal to 15% of the number 40. Choice A (0.9) is incorrect as it is not the result of dividing 6 by 0.15. Choices C (80) and D (90) are incorrect as they do not satisfy the equation 0.15x = 6.

Correct Answer: B

Rationale: The Roman numeral MMXV represents the year 2015. In Roman numerals, M represents 1000, X represents 10, and V represents 5. Therefore, by converting the Roman numeral MMXV into its numerical equivalent (1000 + 10 + 5), it corresponds to the year 2015. Choice A (2001) is incorrect as it would be represented as MM + I, choice C (2051) would be represented as MM + LI, and choice D (2105) would be represented as MMCV in Roman numerals, making them all inaccurate representations of MMXV.