Clocks and Calendars Practice Test 1 with solutions

Angle formed by the minute hand = 20 × 6 = 120°
Angle formed by the hour hand = 30° + 10 = 40°
Angle formed at 1:20 = 120 - 40 = 80°
Length of the arc = $2\mathit{\pi }\mathit{r}\times \frac{80}{360}$
= $2\times \frac{22}{7}\times 12.6\times \frac{80}{360}$ = 17.6 cm