60 discs each of diameter 21 cm and thickness \(\frac{1}{3}\) cm are stacked one above the other to form a right circular cylinder. Find \(\frac{1}{3}\)rd of its volume in m3. (Take \(\pi \) = \(\frac{22}{7}\))
Answer & explanation
Correct answer: option 3
h = 60 × \(\frac{1}{3}\) = 20 cm
Volume = \(\pi \)r2h = \(\frac{22}{7}\) × \(\frac{21}{2}\) × \(\frac{21}{2}\) × 20 = 6930 cm3
\(\frac{1}{3}\)rd of volume = \(\frac{1}{3}\) × 6930 = 2310 cm3 = 2.31 × 10-3 m3