Correct Answer: B

Rationale: To calculate the profit, first determine the total revenue: 7 stands * 11 paintings per stand * $5.50 per painting = $423.50. Then, subtract the total stand expenses ($35 per stand * 7 stands = $245) from the total revenue to get the profit: $423.50 - $245 = $178.50. Therefore, the correct answer is $178.50. Option A is incorrect because it does not account for the stand expenses. Option C is incorrect as it does not consider the total revenue. Option D is incorrect as it overestimates the profit by not deducting the stand expenses.

Correct Answer: A

Rationale: To add mixed numbers, first convert them to improper fractions. 6 3/4 = 27/4 and 8 1/6 = 49/6. Finding a common denominator, we get 27/4 + 49/6 = 81/12 + 98/12 = 179/12 = 14 & 11/12. Therefore, the correct answer is A. Choice B is incorrect as it does not simplify to the correct result. Choice C is in fraction form and not in mixed number form, making it incorrect. Choice D is not the correct sum of the given mixed numbers, so it is also incorrect.

Correct Answer: B

Rationale: The value of pi (π) up to two decimal places is 3.14. Pi is a mathematical constant representing the ratio of a circle's circumference to its diameter and is commonly approximated as 3.14. Choices A, C, and D are incorrect as they do not match the standard approximation of pi up to two decimal places.

Correct Answer: A

Rationale: The correct answer is A: 120 square meters. To find the area of a rectangle, you multiply its length by its width. In this case, the length is 12 meters and the width is 10 meters. Therefore, the area of the room is 12m * 10m = 120 square meters. Choices B, C, and D are incorrect as they do not correctly calculate the area of the room based on its dimensions.

Correct Answer: B

Rationale: Correct! To find out how many girls are in the school, you need to calculate 60% of 500. 60% of 500 is 0.6 * 500 = 300. Therefore, there are 300 girls in the school. Choice A (250 girls) is incorrect because 60% of 500 is not 250. Choice C (200 girls) is incorrect as it is less than 300. Choice D (350 girls) is incorrect as it is more than 300.