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 the perimeter of a hexagonal field with 6 sides, multiply the length of one side (320 feet) by the number of sides (6): 320 x 6 = 1920 feet. The total cost of the fencing material can be calculated by multiplying the perimeter by the cost per foot: 1920 feet x $1.75 = $3360. Therefore, the farmer will need to spend $3,360 on fencing material to enclose the perimeter of the field. Choice A, B, and D are incorrect as they do not accurately calculate the total cost based on the given measurements and cost per foot.

Correct Answer: C

Rationale: Out of the 100 students, 3/4 major in nursing, which equals 75 students. However, only 1/5 of these 75 students will complete the program. Calculating 1/5 of 75 gives us 15 students who will complete the nursing program. Therefore, the correct answer is 15. Choice A (75) is incorrect as it represents the total number of students majoring in nursing, not completing the program. Choices B (20) and D (5) are incorrect calculations and do not align with the information provided in the question.

Correct Answer: C

Rationale: To calculate the average of Pernell's scores, add all the scores together and then divide by the number of scores. (81 + 92 + 87 + 89 + 94) = 443. Now, divide 443 by 5: 443 · 5 = 89, which is the average score.

Correct Answer: D

Rationale: In this study, the dependent variable is the 'Average hours worked per week,' as it relies on the different types of 'Hospital Staff' (the independent variable). The amount of time worked per week varies based on the category of staff being considered. Therefore, the correct choice is D. Choices A and B incorrectly assign the dependent and independent variables to specific staff categories (Nurses and Physicians), which are actually different elements within the study. Choice C incorrectly defines the dependent variable as 'Hospital Staff,' when in fact, it is the 'Average hours worked per week' that is dependent on the type of staff.