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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.
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How will 0.80 be written as a percent?
- A. 40%
- B. 125%
- C. 90%
- D. 80%
Correct Answer: D
Rationale: To convert a decimal to a percent, you multiply by 100. Therefore, 0.80 * 100 = 80%. The correct answer is D. Choice A (40%) is incorrect as 0.80 is not equivalent to 40%. Choice B (125%) is incorrect as it is greater than 100%. Choice C (90%) is incorrect as it does not reflect the correct conversion of 0.80 to a percent.
Your measurement of the width of a door is 36 inches. The actual width of the door is 35.75 inches. What is the relative error in your measurement?
- A. 0.70%
- B. 0.01%
- C. 0.99%
- D. 0.10%
Correct Answer: A
Rationale: To calculate relative error, you use the formula: (|measured value - actual value| / actual value) * 100%. Substituting the values, we get (|36 - 35.75| / 35.75) * 100% = (0.25 / 35.75) * 100% = 0.7%. This means your measurement is off by 0.7% from the actual width of the door. Choice B, 0.01%, is too small as it doesn't reflect the actual difference. Choices C and D are significantly different from the calculated answer and do not represent the accurate relative error in the measurement.
What is the volume of a cube with a side length of 3 cm?
- A. 9 cm³
- B. 27 cm³
- C. 18 cm³
- D. 12 cm³
Correct Answer: B
Rationale: To find the volume of a cube, you cube the length of one side. In this case, the side length is 3 cm, so the volume is calculated as 3 cm * 3 cm * 3 cm = 27 cm³. Therefore, the correct answer is 27 cm³. Choice A (9 cm³), Choice C (18 cm³), and Choice D (12 cm³) are incorrect as they do not correctly calculate the volume of a cube with a side length of 3 cm.
What is the area of a rectangle with a length of 5 cm and a width of 4 cm?
- A. 9 cm²
- B. 20 cm²
- C. 10 cm²
- D. 25 cm²
Correct Answer: B
Rationale: To find the area of a rectangle, you multiply its length by its width. In this case, the length is 5 cm and the width is 4 cm. So, Area = length * width = 5 cm * 4 cm = 20 cm². Therefore, the correct answer is 20 cm². Choice A (9 cm²), Choice C (10 cm²), and Choice D (25 cm²) are incorrect as they do not result from the correct calculation of multiplying the length and width of the rectangle.
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.