Correct Answer: B

Rationale: The correct answer is 13%. To find the percentage of the total staff that is certified and available to work, we first calculate the percentage of staff available, which is 100% - 35% = 65%. Then, we find the percentage of the available staff that is certified, which is 20% of 65% = 0.20 0.65 = 0.13, or 13%.

Correct Answer: A

Rationale: To calculate the total monthly earnings, we first find the commission earned on $5,000 sales, which is 3% of $5,000 = $150. Adding this commission to the $2,000 base salary gives a total of $2,000 + $150 = $2,150. Therefore, the correct total monthly earnings are $2,500. Choice B ($2,150) is incorrect because it only includes the base salary and the commission but miscalculates the total. Choices C ($2,100) and D ($2,300) are also incorrect as they do not account for the correct calculation of the commission on sales.

Correct Answer: C

Rationale: To find out how many milliliters the child should receive, divide the total required dosage of 240 mg by the concentration of the medication, which is 80 mg per 0.8 mL. 240 mg · 80 mg/mL = 3 mL. Since each dose is 0.8 mL, the total dosage for the child would be 3 doses x 0.8 mL per dose = 2.4 mL. Therefore, the correct answer is 2.4 mL. Choice A (0.8 mL) is the concentration of the medication, not the total dose. Choices B (1.6 mL) and D (3.2 mL) are incorrect calculations that do not consider the concentration of the medication and the total required dosage correctly.

Correct Answer: B

Rationale: To simplify the expression, first find a common denominator for the fractions. 3/22 can be rewritten as 6/22. Now, the expression becomes 13/22 - 6/22 - 11. Subtracting 6/22 from 13/22 gives 7/22. Therefore, the correct answer is 7/22. Choice A, 19/22, is incorrect as the subtraction was not done properly. Choices C and D are incorrect as they are not part of the expression being simplified.

Correct Answer: C

Rationale: To solve the equation 4(2x - 6) = 10x - 6, first distribute 4 into the parentheses: 8x - 24 = 10x - 6. Next, simplify the equation by rearranging terms: 8x - 10x = -6 + 24, which gives -2x = 18. Solving for x by dividing by -2 on both sides gives x = -9. Therefore, the correct answer is x = -9. Choice A (x = 5), Choice B (x = -7), and Choice D (x = 10) are incorrect solutions obtained by errors in solving the equation.