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If Mom's car drove 72 miles in 90 minutes, how fast did she drive in feet per second?
- A. 0.8 feet per second
- B. 48.9 feet per second
- C. 0.009 feet per second
- D. 70.4 feet per second
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.
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Which of the following equations does not represent a function?
- A. y = x^2
- B. y = sqrt(x)
- C. x = y^2
- D. y = 2x + 1
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.
A closet is filled with red, blue, and green shirts. If 1/4 of the shirts are green and 1/3 are red, what fraction of the shirts are blue?
- A. 1/2
- B. 1/3
- C. 5/12
- D. 1/4
Correct Answer: C
Rationale: Let the total number of shirts be x. Given that 1/4 of the shirts are green and 1/3 are red, we have Green = x/4 and Red = x/3. To find the fraction of blue shirts, we subtract the fractions of green and red shirts from 1: Blue fraction = 1 - (1/4 + 1/3) = 1 - (3/12 + 4/12) = 1 - 7/12 = 5/12. Therefore, the fraction of blue shirts is 5/12. Choices A, B, and D are incorrect because they do not accurately represent the fraction of blue shirts given the information provided.
What number is 6 equal to 30% of?
- A. 18
- B. 20
- C. 24
- D. 26
Correct Answer: A
Rationale: To find the number that is 30% of 6, you can set up the equation 0.3x = 6. Solving for x gives x = 6 / 0.3 = 20. Therefore, 6 is equal to 30% of 20.
Choice B, 20, is incorrect as it is the result of the calculation. Choice C, 24, and Choice D, 26, are incorrect as they are not the numbers that 6 is equal to 30% of.
If 5y - 7 = 13, what is y?
- A. 4
- B. 5
- C. 6
- D. 7
Correct Answer: A
Rationale: To solve the equation 5y - 7 = 13, start by adding 7 to both sides to isolate the term with y: 5y = 20. Then, divide by 5 to solve for y, which gives y = 4. Therefore, the correct answer is A. Choice B, C, and D are incorrect as they do not yield the correct solution when substituted into the equation. It's important to follow the proper steps in solving linear equations to arrive at the correct answer.
What is the domain for the function y = 1/x?
- A. All real numbers except 0
- B. x > 0
- C. x = 0
- D. x = 1
Correct Answer: A
Rationale: The domain of a function consists of all possible input values that produce a valid output. In the case of y = 1/x, the function is undefined when x = 0 because division by zero is not defined in mathematics. Therefore, the correct domain for y = 1/x is all real numbers except 0 (Choice A). Choice B, x > 0, is incorrect because it excludes the value x = 0. Choice C, x = 0, is also incorrect as x = 0 is not a valid part of the domain due to the function being undefined at this point. Choice D, x = 1, is unrelated to the domain of the function and does not represent the set of valid input values for y = 1/x.