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What is the formula for the area of a circle?
- A. A = πr²
- B. A = 2πr
- C. A = πd
- D. A = 2πd
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.
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Margery plans a vacation with costs for airfare, hotel (5 nights), sightseeing, and meals. If she receives a 10% discount on additional hotel nights, what will she spend?
- A. 1328.35
- B. 1373.5
- C. 1381.4
- D. 1417.6
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.
Four more than a number is 2 less than 5\6 of another number. Which equation represents this?
- A. x + 4 = 5\6y - 2
- B. x + 4 = 2 - 5\6y
- C. 4 + x = 5\6y + 2
- D. x + 4 = 5\6y - 2
Correct Answer: A
Rationale: The equation that represents the relationship is x + 4 = 5\6y - 2.
When is a histogram preferred over a bar graph?
- A. Comparison between categories
- B. Frequency
- C. Percentages
- D. Proportions
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.
Which of the following best describes the relationship in this set of data?
- A. High positive correlation
- B. Low positive correlation
- C. Low negative correlation
- D. No correlation
Correct Answer: B
Rationale: The correct answer is 'B: Low positive correlation.' In a low positive correlation, the variables tend to increase together, but the relationship is not strong. This description fits the data set provided. Choice A, 'High positive correlation,' is incorrect because the correlation is not strong. Choice C, 'Low negative correlation,' is incorrect as the variables are not decreasing together. Choice D, 'No correlation,' is incorrect because there is a relationship between the variables, albeit weak.
Given a double bar graph, which statement is true about the distributions of Group A and Group B?
- A. Group A is negatively skewed, Group B is normal.
- B. Group A is positively skewed, Group B is normal.
- C. Group A is positively skewed, Group B is neutral.
- D. Group A is normal, Group B is negatively skewed.
Correct Answer: B
Rationale: The correct answer is B. In statistical terms, a positively skewed distribution means that the tail on the right side of the distribution is longer or fatter than the left side, indicating more high values. Therefore, Group A is positively skewed. Conversely, an approximately normal distribution, also known as a bell curve, is symmetrical with no skewness. Hence, Group B is normal. Choices A, C, and D are incorrect because they do not accurately describe the skewness of Group A and the normal distribution of Group B as depicted in a double bar graph.