Correct Answer: C

Rationale: An equation represents a function if each input (x-value) corresponds to exactly one output (y-value). In the equation x = y^2, for a single x-value, there are two possible y-values (positive and negative square root), violating the definition of a function. This violates the vertical line test, where a vertical line intersects the graph in more than one point for non-functions. Choices A, B, and D all pass the vertical line test and represent functions, making them incorrect answers.

Correct Answer: D

Rationale: To convert miles per hour to feet per second, first convert time to hours: 90 minutes = 1.5 hours. Then, calculate the speed in miles per hour: 72 miles in 1.5 hours = 48 mph. Finally, convert mph to feet per second using the conversion factor 1 mph = 1.47 feet per second: 48 mph * 1.47 = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choices A, B, and C are incorrect because they do not reflect the correct conversion from miles per hour to feet per second.

Correct Answer: A

Rationale: 18/5 = 3 with a remainder of 3, so it is 3 3/5. 3 1/15 is equivalent to 46/15 which is greater than 18/5 3 1/18 converts to 55/18 which is also greater than 18/5 3 1/54 converts to 163/54

Correct Answer: C

Rationale: A valid hypothesis must be a testable statement that predicts a relationship between variables. Option C is the only statement that presents a clear cause-and-effect relationship between the amount of poison given and the time it takes for the rat to die. Option A is descriptive without predicting an outcome, option B is a question rather than a statement, and option D is a general fact about poison and rats, lacking a specific hypothesis for testing.

Correct Answer: D

Rationale: To find the sum of fractions, they need to have a common denominator. In this case, the common denominator is 8. So, 3/4 = 6/8. Adding 6/8 and 5/8 gives 11/8, which simplifies to 1 3/8. Therefore, the correct answer is 1 3/8, which corresponds to choice A. Choices B, C, and D are incorrect as they do not represent the correct sum of 3/4 and 5/8.