Correct Answer: A

Rationale: The key difference between a histogram and a bar graph is that a bar graph has gaps between the bars, while a histogram does not. This feature helps in visually distinguishing between the two. Choice B is incorrect because both types of graphs can show frequency. Choice C is incorrect as both graphs can be used for comparison. Choice D is incorrect as both types of graphs can have labels for better understanding.

Correct Answer: B

Rationale: To calculate a 30% decrease in 340 mg, you multiply 340 by 0.3, which equals 102 mg. Subtracting this from the current dosage gives 340 - 102 = 238 mg. Therefore, the correct answer is 238 mg. Choice A (70 mg) is incorrect because it represents a 70% decrease, not 30%. Choice C (270 mg) is incorrect as it does not reflect the correct calculation for a 30% decrease. Choice D (340 mg) is the initial dosage and not the reduced dosage after a 30% decrease.

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: A

Rationale: The correct answer is A: 7:1. To find the ratio, divide the number of students with brown eyes (14) by the number of students with green eyes (2), which equals 7. Therefore, the ratio of students with brown eyes to students with green eyes is 7:1. Choice B (7:2) is incorrect as it does not accurately represent the ratio of students with brown eyes to green eyes. Choice C (14:2) is incorrect because the ratio should be simplified, and 14:2 simplifies to 7:1. Choice D (14:1) is incorrect as it does not consider the number of students with green eyes.

Correct Answer: A

Rationale: To differentiate between the three types of graphs - scatterplots, a linear graph will display a straight line, a quadratic graph will have a U-shape, and an exponential graph will show a rapid rise or fall in one direction. Choice B is incorrect because linear graphs are represented by straight lines, not curved lines. Choice C is incorrect as linear graphs do not exhibit zigzag patterns, and exponential graphs do not typically result in flat lines. Choice D is incorrect because quadratic graphs form a U-shape, not a W-shape, and exponential graphs do not represent vertical lines.