Answer:
540 good parts were produced yesterday
Explanation:
1. Let's review the information given to us to answer the question correctly:
Machine's error rate = 10% or 0.1
Hourly production of the machine = 30 parts
Number of hours the machine was shut down yesterday = 4 hours
2. How many good parts did it produce yesterday?
For answering this question, we will make the following calculation:
Yesterday's good production = (Total hours the machine works * Hourly production of the machine) - (Total hours the machine works * Hourly production of the machine * Machine's error rate)
Replacing with the real values, we have:
Yesterday's good production = (20 * 30) - (20 * 30 * 0.1)
Yesterday's good production = 600 - 60
Yesterday's good production = 540 parts