A cylindrical milk can has the radius and height shown. The milk in the full can is poured into 500 mL packets. How many packets can be filled completely? (Take π = 22/7.)
Class 8MensurationMensuration
A31
B30
C15
D123
Step-by-Step Solution
Volume =722×142×25=15400cm3=15.4 litres =15400 mL. 15400÷500=30.8, so 30 packets are filled completely.
Answer: B) 30
Key idea: Surface area and volume of a cylinder
A cylinder is a circle stacked vertically. Two measurements: radius r and height h.
**Curved surface area (CSA) = 2πrh** (imagine 'unrolling' the curved surface — it becomes a rectangle of width 2πr and height h).
**Total surface area (TSA) = 2πr2+2πrh=2πr(r+h)** (curved surface + two circular ends).
**Volume = πr2h** (area of circular base × height).
Use π = 22/7 when r is a multiple of 7; otherwise π ≈ 3.14.
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