Answer: 40 seconds per worksheet
Explanation:
From the information given in the question, we are informed that Robert took 8 minutes to complete his 12 worksheets.
Based on this, his unit rate of completing worksheets will be given as:
= 8 minutes / 12
= 480 seconds / 12
= 40 seconds per worksheet
Note 1 minute = 60 seconds
8 minutes = 8 × 60 = 480 seconds