Correct Answer: A

Rationale: The correct formula for the area of a circle is A = πr², where π is a mathematical constant approximately equal to 3.14159 and r is the radius of the circle. Choice B, A = 2πr, represents the circumference of a circle, not the area. Choice C, A = πd, incorrectly uses the diameter (d) instead of the radius in the formula for area. Choice D, A = 2πd, is also related to the circumference of the circle, not the area. Therefore, option A is the only correct formula for calculating the area of a circle.

Correct Answer: A

Rationale: To calculate Margery's total cost, we first need to find the cost without the discount. Let's say the original cost is x. With a 10% discount, she saves 10% of the cost of additional hotel nights. Since she is staying for 5 nights, the discount applies to 4 additional nights (5 - 1 night already included). Therefore, she saves 10% of 4 nights' cost. If x is the cost of 1 night, the total cost without discount is 5x. With the 10% discount, she saves 0.1 * 4x = 0.4x. So, the cost after discount is 5x - 0.4x = 4.6x. Given that the total cost is 5x for 5 nights, we can equate 5x to 4.6x to find x. Solving for x, we get x = Total cost / 5 = 5x / 5 = 4.6x / 5. Therefore, x = 4.6x / 5, which simplifies to x = 0.92 * 5x. This means 1 night's cost is 0.92 times the total cost for 5 nights. Given the total cost is $1328.35, we find the cost for 1 night is $1328.35 / 5 = $265.67. So, Margery will spend $1328.35 for her vacation.

Correct Answer: B

Rationale: To find the total cost of Susan's outfit, you need to add the prices of the dress, shoes, and accessories together. $69.99 + $39.99 + $34.67 = $144.65. Therefore, the correct total cost of her outfit is $144.65. Choice A ($139.65) is incorrect as it does not account for the full cost of all items. Choice C ($145.55) is incorrect as it includes an extra amount not part of the given prices. Choice D ($144.65) is incorrect due to a duplication of the correct answer.

Correct Answer: C

Rationale: The correct answer is C. A rational number can be a whole number, fraction, or decimal. A rational number is any number that can be expressed as a ratio of two integers (where the denominator is not zero), which includes whole numbers, fractions, and decimals. Choice A is incorrect because rational numbers are not limited to being whole numbers. Choice B is incorrect because a rational number can be a fraction, decimal, or whole number. Choice D is incorrect because rational numbers can definitely be decimals, as long as the decimal representation is either terminating or repeating.

Correct Answer: B

Rationale: Histograms are specifically designed to display the frequency distribution of continuous data, showing the distribution of values over intervals or bins. On the other hand, bar graphs are used to compare different categories or discrete data points. Therefore, the correct answer is B. Choices A, C, and D are incorrect because histograms are not primarily used for comparing categories, percentages, or proportions, but rather for visualizing the distribution of frequencies within data intervals.