2021 · Q65
The minute hand of a clock is 21 cm long. What is the area on the face of the clock described by the minute hand between 10.10 a.m and 10.30 a.m ? (take π = 22/7)
Elementary MathematicsCircles
- A231 cm²
- B331 cm²
- C462 cm²
- D492 cm²
Explanation
From 10:10 to 10:30 the minute hand turns through 20 minutes = 120°. The swept area is (120/360)·π·21² = (1/3)·(22/7)·441 = 462 cm². This is option (c).