25) B

Let us say the period of time is 1 hour.
In one hour, the minute hand will sweep the entire 360º
The hour hand will sweep = 360 ÷ 12 = 30º

Let us say the minute hand is the radius of a circle. Radius = 8.4cm ≈ 8cm
Area of the circle = πr² = (8)²π = 64π
Since the minute hand will sweep the entire 360º, the area it will sweep would be 64π

Let us say the hour hand is the radius of a different circle. Radius = 6.3 cm ≈ 6
Area of the circle = πr² = (6)²π = 36π
Since the hour hand will only sweep the 30º, the area it will sweep would be (1/12) x 36π = 3π

Ratio = 64π ÷ 3π
The πs cancel each other giving : 64 ÷ 3 = 64 : 3

Hence, B is the answer.

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