Correct Answer: D

Rationale: To convert yards to feet, you need to know that 1 yard is equal to 3 feet. Therefore, to find out how many feet are in 9 yards, you multiply 9 by 3, which equals 27 feet. Choice A (45 ft) is incorrect as it miscalculates by multiplying 9 by 5 instead of 3. Choice B (18 ft) incorrectly multiplies 9 by 2. Choice C (36 ft) is incorrect as it doubles the answer of 18 feet, which is also an incorrect calculation.

Correct Answer: A

Rationale: To convert Fahrenheit to Celsius, you start by subtracting 32 from the Fahrenheit temperature and then divide the result by 1.8. This formula accounts for the freezing point of water at 32°F and the conversion factor to Celsius. To convert Celsius to Fahrenheit, you multiply the Celsius temperature by 1.8 and then add 32. This process takes into consideration the conversion factor from Celsius to Fahrenheit and the freezing point of water. Choice B is incorrect as dividing by 2 instead of 1.8 would yield an inaccurate conversion. Choice C is incorrect as it involves incorrect operations for both conversions. Choice D is incorrect as subtracting 30 instead of 32 for Fahrenheit to Celsius and multiplying by 2 instead of 1.8 for Celsius to Fahrenheit would provide incorrect results.

Correct Answer: B

Rationale: To find the area of a square, you square the length of one side. In this case, the side length is 3.1m. So, Area = side² = 3.1m 3.1m = 9.61m². Therefore, the correct answer is 9.61m². Choice A (12.4m²) is incorrect as it is the result of multiplying 3.1m by 4 instead of squaring it. Choice C (6.2m²) is incorrect as it is half of the correct answer. Choice D (9.1m²) is incorrect as it is the result of squaring the wrong value (3.1²).

Correct Answer: D

Rationale: To calculate a 10% tip on a bill of $28.40, you would first find 10% of $28.40, which is $2.84. Since you typically round up when leaving a tip, the estimated gratuity would be $3.00. Option A is incorrect as it is too high for a 10% tip. Option B is incorrect as it is too high. Option C is incorrect as it is too low for a 10% tip. Therefore, the correct answer is $3.00.

Correct Answer: C

Rationale: The independent variable in a function is the variable that is being manipulated or changed to obtain different values. In the equation f(t) = 4t + 9, the variable 't' is the independent variable. It is the variable that the function f(t) depends on, and changing its value will result in different outputs for the function. The other choices, 'f', '9', and '4', are not the independent variable as they do not represent the variable that is being manipulated to determine the function's output.