Correct Answer: B

Rationale: To convert miles per hour to feet per second, you need to convert miles to feet and minutes to seconds. First, convert 72 miles to feet using the conversion factor 1 mile = 5280 feet: 72 miles * 5280 feet/mile = 380160 feet. Then, convert 90 minutes to seconds: 90 minutes * 60 seconds/minute = 5400 seconds. Now, to find the speed in feet per second, divide the distance traveled in feet by the time in seconds: 380160 feet / 5400 seconds = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choice A, 0.8 feet per second, is incorrect as it is a much lower speed. Choice C, 0.009 feet per second, is also incorrect as it is too low. Choice D, 70.4 feet per second, would be correct if the conversion calculations were accurate, but in this case, it's not the correct answer.

Correct Answer: C

Rationale: To find the fourth person's share, subtract the fractions paid by the first three people from the total bill (1). The first person pays 1/5, the second person pays 1/3, and the third person pays 1/12. Adding these fractions gives 7/15. Subtracting this from 1 gives the fourth person's share as 8/15, which simplifies to 4/5. Therefore, the fourth person pays 4/5 of the bill. Option A (1/4) is incorrect because it does not consider the fractions paid by the first three people. Option B (13/60) is incorrect as it is not the remainder after subtracting the first three fractions from 1. Option D (1/4) is a duplicate of Option A and is also incorrect.

Correct Answer: C

Rationale: The correct answer is C: 'Irrational or rational.' When you multiply two irrational numbers, the result can be either irrational or rational. For example, multiplying the square root of 2 (√2) by itself results in the rational number 2. This shows that the product of two irrational numbers can lead to a rational result. Choices A, B, and D are incorrect because the product of two irrational numbers is not limited to being irrational; it can also be rational.

Correct Answer: C

Rationale: To find the fraction of blue shirts, subtract the fractions of green and red shirts from 1. Green shirts are 2/5 and red shirts are 1/3, which sum up to 11/15. Therefore, blue shirts would be 1 - 11/15 = 4/15. So, the correct answer is 4/15. Choice A (4/15) is incorrect as it represents the overall fraction of green shirts. Choice B (1/5) is incorrect as it does not account for the fractions of green and red shirts. Choice D (1/2) is incorrect as it does not consider the given fractions of green and red shirts.

Correct Answer: B

Rationale: To add 1/6 and 1/2, you need a common denominator, which is 6. So, 1/6 + 3/6 = 4/6. Simplifying 4/6 gives 2/3, which is the correct answer (1/3). Choices A, C, and D are incorrect as they do not represent the correct sum of the fractions 1/6 and 1/2.