Surface Areas and Volumes — Question Ex 13.4 Q4
Back to all questionsA container, opened from the top and made up of a metal sheet, is in the form of a frustum of a cone of height 16 cm with radii of its lower and upper ends as 8 cm and 20 cm, respectively. Find the cost of the milk which can completely fill the container, at the rate of Rs 20 per litre. Also find the cost of metal sheet used to make the container, if it costs Rs 8 per 100 cm2.

CBSE Class 10 Surface Areas and Volumes — Complete Guide
This chapter carries 5-6 marks covering combination of solids, conversion problems, and frustum of a cone.
Quick Revision: Key Concepts
- Combination: Add CSAs (subtract hidden faces for TSA), add volumes
- Conversion: Volume is conserved when solid is melted and recast
- Frustum: V = ⅓πh(R² + r² + Rr), l = √[h² + (R−r)²]
- Water flow: Volume = cross-section area × speed × time
Most Important Questions
- SA and volume of combined solids (tent, capsule, toy)
- Solid melted and recast into smaller solids (find number)
- Frustum volume and surface area (bucket problems)
- Water flow and pipe problems
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