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: 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.

Correct Answer: B

Rationale: To calculate how many gallons of gas Robert needs for the 1,800-mile trip, divide the total distance by the car's mileage per gallon: 1,800 miles · 30 mpg = 60 gallons. Since his tank holds 12 gallons, Robert will need 60 gallons · 12 gallons per tank = 5 tanks of gas for the trip. Choice A (4 tanks), Choice C (6 tanks), and Choice D (7 tanks) are incorrect as they do not correctly calculate the number of tanks needed based on the car's mileage and tank capacity.

Correct Answer: D

Rationale: The correct answer is D, which is 4 quarts in a gallon. In the US customary system, there are 4 quarts in a gallon. Choice A is incorrect as it represents the equivalent of a quart, not a gallon. Choice B and C are incorrect as they are smaller quantities than a gallon and do not match the conversion of quarts to a gallon.

Correct Answer: A

Rationale: To solve the equation x + 5 = x - 3, we aim to isolate x. By subtracting x from both sides, we get 5 = -3, which is not possible. This indicates that the equation has no solution. Therefore, the correct answer is x = -5. Choices B, C, and D are incorrect as they do not yield a valid solution when substituted back into the original equation.