Correct Answer: B

Rationale: During January, Dr. Lewis worked 20 shifts. Shifts for January = 20. During February, she worked three times as many shifts as she did during January. Shifts for February = (20)(3) = 60. During March, she worked half the number of shifts she worked in February. Shifts for March = (60)(1/2) = 30. Therefore, the correct equation to describe the number of shifts Dr. Lewis worked in March is 'shifts = (20)(3)(1/2)', representing the calculation based on the given scenario. Choices A, C, and D do not accurately represent the correct mathematical relationship between the shifts worked in the different months, making them incorrect.

Correct Answer: B

Rationale: The average length of a human eyelash is approximately one centimeter. A nanometer is too small to describe the length of an eyelash. A meter and a kilometer are much longer lengths and not suitable to describe the average human eyelash.

Correct Answer: B

Rationale: The rate of change refers to how one quantity changes concerning another quantity. In this scenario, the rate of change is the amount of snow melting per day, which is 5 centimeters. This is determined by the slope of the graph, indicating a decrease in snow depth. Choices C and D incorrectly describe an increase in snow depth, while choice A exaggerates the rate of snow melting compared to the actual value of 5 centimeters per day.

Correct Answer: B

Rationale: Start by solving the multiplication and parentheses. The answer is -20.

Correct Answer: C

Rationale: To estimate the number of miles Lauren will drive per day, the total distance can be rounded to 1,500 miles. Divide this by the number of days she plans to drive, which is 5. 1,500 miles / 5 days = 300 miles per day. Therefore, a reasonable estimate for the number of miles she will drive per day is 300. Choice A (240 miles) is too low, Choice B (260 miles) is slightly low, and Choice D (340 miles) is too high when considering the total distance and the number of days Lauren plans to drive.