Correct Answer: B

Rationale: To find the number of girls in the class, we need to calculate 40% of the total number of students, which is 30. 40% of 30 is 0.40 * 30 = 12 girls. Therefore, there are 12 girls in the class. Choice A, 18 girls, is incorrect as it miscalculates the percentage. Choice C, 15 girls, is incorrect as it misrepresents the correct calculation. Choice D, 10 girls, is incorrect as it underestimates the number of girls in the class.

Correct Answer: B

Rationale: To find the number of people who voted, you need to calculate 9.5% of the total population of 51,623. 9.5% of 51,623 is approximately 0.095 x 51,623 = 4,999.85, which is rounded to approximately 5,000 people. Therefore, the correct answer is 5,000 people. Choice A, 3,000 people, is incorrect as it is lower than the calculated value. Choice C, 7,000 people, is incorrect as it is higher than the calculated value. Choice D, 10,000 people, is incorrect as it is much higher than the calculated value.

Correct Answer: C

Rationale: When a rectangle is scaled by a factor of 2, both the length and width are multiplied by 2. The new dimensions become width = 5 * 2 = 10 inches and length = 10 * 2 = 20 inches. Therefore, the new perimeter is calculated as 2 * (10 + 20) = 60 inches. Choice A, B, and D are incorrect as they do not reflect the correct calculation based on scaling the dimensions of the rectangle.

Correct Answer: A

Rationale: To find the discounted price, you first calculate 20% of the original price: 20% of $80 is $16. Subtracting this discount amount from the original price gives the final price: $80 - $16 = $64. Therefore, the final price after a 20% discount on a product originally priced at $80 is $64. Choice B, $60, is incorrect because it does not account for the correct discount amount. Choice C, $70, is incorrect as it does not reflect the reduction due to the 20% discount. Choice D, $66, is incorrect as it miscalculates the discounted price.

Correct Answer: B

Rationale: To find the percentage of trips where the person chose the longest route, divide the number of longest route trips (3) by the total number of trips (9) and multiply by 100. This gives (3/9) * 100 = 33.33%, which can be rounded to 33%. Therefore, the correct answer is B. Choice A (0.25), C (0.5), and D (0.75) are incorrect because they do not accurately represent the percentage of trips where the longest route was chosen based on the given information.