1. The diameter of a wheel is 0.5 m. How far does it travel in 10 revolutions? { Take π' = 3.14 }
    0.5 × 3.14 × 10
   ﹦1.570796327 × 10
   ﹦15.70796327

2. A coin rolling along a straight line covers 110 cm in 14 revolutions. Find the diameter of the coin { Take π' = 22/7 }
   110 ÷ 14 ÷ 22/7
  ﹦55/7 × 7/22
  ﹦5/2

↓超級唔肯定呢***

3. The difference between the radii of two circles is 3 cm. Find the difference in their circumferences. { Express your answer in terms of π }
   
  Let y be the smaller radius, y+3 be the larger radius.
   [ ( y ﹢3 ) × 2 × π ] ﹣ ( y × 2 ×  π )
  ﹦( 2y ﹢ 6 × π ) - 2πy
  ﹦2πy ﹢ 6π  - 2πy
  ﹦6π

希望幫到你啦*