A hallow cylinder made up of copper, the difference between its outer and inner C.S.A is 1232 cm² and cylinder holds 4312 cm³ water. If the cost of copper is 10/cm³. Find the cost of copper used in cylinder, if height of cylinder is 28 cm?
a) Rs. 44120
b) Rs. 43120
c) Rs. 43210
d) Rs. 45000
Sol:
Volume of cylinder = 4312
πr²h = 4312
r = 7 cm.
&
2 π (R-r) h = 1232
R=14 cm
∴ thickness of hallow cylinder is (14 – 7) = 7 cm
Volume of hollow cylinder = π (R –r)² h = 22/7×7×7×28
=>4312 cm3
Hence total cost of copper used = 4312 × 10 = 43120
