The angular distance covered by the minute hand in 1 Hr 20 minutes is :

480°

Movement of minute hand in 60 minutes =  360 degrees

So, the angular speed of the minute hand = 6 degrees per minute

In 60 minutes / 1 hour, angular distance cover by minute hand = 6 × 60 = 360 degrees

In 20 minutes, angular distance cover by minute hand = 6 × 20 = 120 degrees

So, the angular distance covered by the minute hand in 1 hour 20 minutes

= 360 + 120

= 480 degrees