The correct answer is:
639.4 minutes.
Explanation:
Saturn takes 10 hours, 39 minutes and 24 seconds to make a complete rotation.
10 hours × 60 minutes per hour = 600 minutes.
600 minutes + 39 minutes = 639 minutes.
24 seconds out of 60 seconds per minute = 24/60 = 0.4.
This gives us 639+0.4 = 639.4 minutes.