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.

Correct Answer: A

Rationale: The slope of the equation C = 50 + 75D is 75. This means that for each additional gigabyte used (represented by D), the cost (represented by C) increases by 75 dollars. Therefore, the correct interpretation of the slope is that it is 75 dollars per gigabyte. Choice B, 75 gigabytes per day, is incorrect as the slope does not represent the rate of data usage per day. Choice C, 50 dollars per day, is incorrect as it does not reflect the relationship between gigabytes used and the cost. Choice D, 50 dollars per gigabyte, is incorrect as it does not match the slope value of 75 in the equation.

Correct Answer: C

Rationale: Let r be the number of red cans and b be the number of blue cans. The total cans equation is r + b = 10. The total cost equation is r + 2b = 16. By solving these equations simultaneously, we find r = 4. Therefore, Jessica bought 4 red cans. Choice A, 2 red cans, is incorrect because it does not satisfy the total cans or total cost condition. Choices B and D are also incorrect as they do not fulfill both conditions simultaneously.

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.

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.