Correct Answer: C

Rationale: Reducing the rat's speed by 50% means it will take twice as long to finish the maze. Since the original time is 3 minutes, doubling that gives 6 minutes. Therefore, the total time will be 6 minutes, making the correct answer C. Choice A (3 minutes) is the original time it takes the rat to finish the maze, not the time with the backpack. Choice B (4 minutes) is not correct as reducing the speed by 50% would double the original time. Choice D (1.5 minutes) is incorrect as halving the time is not the effect of reducing the speed by 50%.

Correct Answer: C

Rationale: To add mixed numbers, convert them to improper fractions. 7 2/3 = 23/3 and 5 5/12 = 65/12. Adding them results in 233/12. Converting this improper fraction back to a mixed number gives 19 5/12, which simplifies to 13 1/12. Therefore, the correct answer is 13 1/12.\nChoice A (11 1/12) is incorrect as it does not represent the correct sum of the given mixed numbers. Choice B (12 1/4) is incorrect as it is not the result of adding 7 2/3 and 5 5/12. Choice D (14 1/6) is incorrect as it is not the correct sum of the provided mixed numbers.

Correct Answer: A

Rationale: The correct answer is A: 28. To find 28% of 100, you multiply 0.28 (the decimal equivalent of 28%) by 100. This calculation results in 28. Therefore, 28% of 100 is 28. Choice B, 20, is incorrect as it represents 20% of 100. Choice C, 25, is incorrect as it represents 25% of 100. Choice D, 30, is incorrect as it represents 30% of 100.

Correct Answer: B

Rationale: To convert yards to feet, you multiply by 3, as 1 yard is equal to 3 feet. Therefore, 3 yards equals 3 x 3 = 9 feet. Choice A (18 feet) is incorrect because it multiplies by 2 instead of 3. Choice C (12 feet) is incorrect as it multiplies by 4 instead of 3. Choice D (27 feet) is incorrect as it multiplies by 9 instead of 3.

Correct Answer: C

Rationale: In Roman numerals, XL represents 40, and IV represents 4. When XL (40) is combined with IV (4), it forms XLIV, which corresponds to the number 44. Therefore, the correct answer is 44. Choice A (34) is incorrect as it does not consider the value of XL and IV. Choice B (54) is incorrect as it miscalculates the value of XL. Choice D (24) is incorrect as it does not account for the value of XL.