The radius of a cone is raised by 20%, while the height is reduced by 10%. What is the percentage change in the volume of the cone?
29.6% increase
\(V = \dfrac{{1}}{{3}}\pi r^2 h\)
New volume = \(\dfrac{{1}}{{3}}\pi (1.2r)^2(0.9h) = \dfrac{{1}}{{3}}\pi \times 1.44r^2 \times 0.9h = 1.296 \times V\)
Percentage increase = \((1.296-1) \times 100 = \mathbf{{29.6\%}}\)
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Important Questions from 3-D Mensuration
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