2024 · Q38
From a circular metal plate of radius 7 cm and thickness 0.16 mm, a sector is cut off containing an angle 150°. The remaining piece is moulded into a spherical bead of radius r. What is the value of r in cm?
Elementary MathematicsMensuration
- A0.35
- B0.7
- C1.05
- D1.4
Explanation
The remaining plate has volume (210/360)π(7)²(0.016), which is moulded into a sphere of volume (4/3)πr³. Equating gives r³ = 0.343. Hence r = 0.7 cm, option (b).