At what angle in degrees does the hour hand rotate if the minute hand is rotated 120 °?

The entire dial of the watch contains 360 ° and is divided into 12 parts-hours. This means that after 1 hour, the hour hand passes 1/12 of the entire dial, or 360 ° / 12 = 30 °.

In turn, the minute hand goes a full circle for 1 hour – 360 °.

According to the condition of the task, the minute hand is rotated by 120 °, which is 120 ° / 360 ° = 1/3 hour or 20 minutes.

During this time, the hour hand should move 1/3 of 30 °, which is 30 ° * 1/3 = 10 °.