A charter bus driver drove at an average speed of 65 mph for 305 miles. If he stops at a gas station for 15 minutes, then drives another 162 miles at an average speed of 80 mph, how long will it have been since he began the trip?

Correct Answer: D

Rationale: To find the total time, we first calculate the time taken for the first leg of the trip by dividing the distance of 305 miles by the speed of 65 mph, which equals 4.69 hours. After that, we add the 15 minutes spent at the gas station, which is 0.25 hours. Next, we calculate the time taken for the second leg of the trip by dividing the distance of 162 miles by the speed of 80 mph, which equals 2.03 hours. Adding these times together (4.69 hours + 0.25 hours + 2.03 hours) gives us a total time of 6.97 hours. Therefore, it will have been 6.97 hours since the driver began the trip. Choice A is incorrect as it does not account for the time spent driving the second leg of the trip. Choice B is incorrect as it only considers the time for the first leg of the trip and the time spent at the gas station. Choice C is incorrect as it misses the time taken for the second leg of the trip.

Correct Answer: A

Rationale: The correct equation to represent the amount of money Andy will have saved is y = 15 + 28x. This is because Andy has already saved $15 and plans to save an additional $28 per month. Therefore, the total amount he will have saved can be calculated by adding the initial $15 to the monthly savings of $28 (28x), resulting in y = 15 + 28x. Choices B, C, and D do not correctly account for the initial $15 that Andy has saved and therefore do not represent the total amount correctly.

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: B

Rationale: The correct answer is B: 'The grades students received.' In this scenario, the grades students received are the dependent variable because they are influenced by the number of hours spent studying. The grades are the outcome that is being measured based on the manipulation or observation of the independent variable, which in this case is the number of hours spent studying. Choices A, C, and D are incorrect. The number of hours spent studying is the independent variable being manipulated or observed, the subjects students studied is not directly related to the dependent variable, and the number of students in the study is not the variable being measured or influenced by the independent variable.

Correct Answer: C

Rationale: A graph that has a y-intercept of 0 indicates a proportional relationship because the starting value is 0, and no amount is added to or subtracted from the term containing the slope. In this case, choice C is correct as it has a y-intercept of 0, which aligns with the characteristics of a proportional relationship. Choices A, B, and D have non-zero y-intercepts, indicating a starting value other than 0, which does not represent a proportional relationship.