Which of the following is equivalent to 0.0009?

Correct Answer: A

Rationale: The correct answer is A: 0.09%. To convert 0.0009 to a percentage, move the decimal point four places to the right and add a percentage sign. Therefore, 0.0009 is equal to 0.09%. Choice B (9%) is incorrect as it represents 0.09 without the decimal point adjustment. Choice C (0.01%) is incorrect as it represents 0.0009 with one less zero. Choice D (0.90%) is incorrect as it represents 0.9 not 0.0009.

Correct Answer: A

Rationale: First, convert the child's weight from pounds to kilograms: 44 lb · 2.2 = 20 kg. Next, calculate the required dosage: 20 kg 20 mg/kg = 400 mg. Since each tablet contains 80 mg, divide the total dosage by the dosage per tablet: 400 mg · 80 mg/tablet = 5 tablets. Therefore, the correct answer is 5 tablets. Choice B is incorrect because it does not account for the actual number of tablets needed. Choice C is incorrect as it is an underestimation of the required tablets. Choice D is incorrect as it is an underestimation of the required tablets.

Correct Answer: A

Rationale: To convert milliliters to liters, you divide by 1000 since 1000 milliliters make up 1 liter. In this case, 5000 milliliters divided by 1000 milliliters per liter equals 5 liters (5000 mL · 1000 mL/L = 5 L). Therefore, the correct answer is A: 5 liters. Choice B, 4 liters, is incorrect because 5000 milliliters is equivalent to 5 liters, not 4. Choice C, 6 liters, is incorrect as it is not the accurate conversion from milliliters to liters in this case. Choice D, 5.5 liters, is incorrect as it does not reflect the correct conversion of 5000 milliliters to liters, which is 5 liters.

Correct Answer: D

Rationale: The difference between the original price ($200) and the new price ($150) is $50. To find the percentage decrease, divide the difference by the original price and multiply by 100: ($50 / $200) 100 = 25%. Therefore, the correct answer is D, meaning the price decreased by 25%. Choices A, B, and C are incorrect as they do not accurately represent the percentage decrease in price.

Correct Answer: B

Rationale: In the metric system, there are 1000 grams in 1 kilogram. To convert kilograms to grams, you multiply the number of kilograms by 1000. Therefore, 4 kilograms would equal 4000 grams. Choice A (400 grams) is incorrect because it is the result of multiplying by 100, not 1000. Choice C (40 grams) is incorrect as it is the result of dividing by 1000 instead of multiplying. Choice D (100 grams) is incorrect as it is a random figure and not the correct conversion from kilograms to grams.

Correct Answer: C

Rationale: To determine the number of trees, reduce the field dimensions by 10 meters (5 meters of space on each side). The effective area is 640 meters 770 meters. Each tree occupies 10 meters 10 meters. Dividing the effective area by the space for each tree gives: (640 770) · (10 10) = 286 trees. Choice A, B, and D are incorrect because they do not consider the reduction in field dimensions and the space required for each tree.

Correct Answer: A

Rationale: Robert spent a total of $7.95 on three comics ($2.65 each). When he paid with a $20 bill, the change he received can be calculated by subtracting the total cost from the payment amount: $20 - $7.95 = $12.05. Therefore, Robert received $12.05 in change. Choice B ($11.05) is incorrect because it doesn't reflect the correct calculation. Choice C ($10.00) is incorrect as it doesn't consider the total cost of the comics. Choice D ($13.50) is incorrect as it overestimates the change Robert received.

Correct Answer: B

Rationale: To solve the equation 4y - 6 = 14 for y, isolate y by adding 6 to both sides: 4y = 14 + 6 => 4y = 20. Then, divide by 4 to solve for y: y = 20 · 4 = 5. Therefore, the correct answer is 5. Choice A is incorrect as it does not represent the correct solution to the equation. Choice C is incorrect as it is not the solution obtained after correctly solving the equation. Choice D is incorrect as it is not the correct solution to the given equation.

Correct Answer: A

Rationale: The correct answer is A: 28. To find 28% of 100, you multiply 0.28 (the decimal equivalent of 28%) by 100. This calculation results in 28. Therefore, 28% of 100 is 28. Choice B, 20, is incorrect as it represents 20% of 100. Choice C, 25, is incorrect as it represents 25% of 100. Choice D, 30, is incorrect as it represents 30% of 100.