Final answer:
The inequality 60 ≤ 0.5x + 2.5 ≤ 250 is used to determine mammals with brain weights between 60 and 250 pounds. After isolating x, the weight range of the mammals' brains is found to be 115 to 495 pounds.
Step-by-step explanation:
The biologist has recorded average weights for mammalian brains and is using an inequality to determine which mammals have brain weights falling within a certain range. The inequality is 60 ≤ 0.5x + 2.5 ≤ 250, where x represents the weight of the mammals whose brains weigh between 60 and 250 pounds. To solve for x, we must first subtract 2.5 from all parts of the inequality to get 57.5 ≤ 0.5x ≤ 247.5. Then, divide everything by 0.5, resulting in 115 ≤ x ≤ 495. This means that the mammals considered in this inequality have a brain weight that falls within the range of 115 pounds to 495 pounds.