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.

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: D

Rationale: To find the product of 32 and 5, you simply multiply the two numbers: 32 5 = 160. Therefore, when expressed in decimal form, the answer is 1.6. Choices A, B, and C are incorrect as they do not represent the correct multiplication result in decimal form. Choice A is way too small, choice B is also too small, and choice C is close but still not the correct result.

Correct Answer: B

Rationale: In military time, the afternoon and evening hours are represented by adding 12 to the standard time. Therefore, 6:20 P.M. would be equivalent to 18:20 in military time. To convert from P.M. to military time, simply add 12 hours to the given time. Choice A, '620,' is incorrect because it does not account for converting to military time. Choice C, '6020,' is incorrect as military time uses a 24-hour clock format, and the hour digit should not exceed 23. Choice D, '6200,' is incorrect as it does not follow the military time format where the hour part ranges from 00 to 23.

Correct Answer: C

Rationale: If a horse can trot around a track twice in 10 minutes, it completes one circle in 5 minutes. To determine how many times it will circle the track in half an hour (30 minutes), divide the total time by the time taken for one circle: 30 minutes / 5 minutes per circle = 6 times. Therefore, the horse will circle the track 6 times at the same speed in half an hour. Choice A, 3 times, is incorrect as it does not consider the correct time taken for a single circle. Choice B, 5 times, is incorrect as it miscalculates the total number of circles within half an hour. Choice D, 10 times, is incorrect as it overestimates the number of circles the horse can complete in the given time frame.