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Find the values and arrange in increasing order:

(A) If each edge of a cube is increased by 20%, then the percentage increase in its volume is:

(B) If the radius of a cylinder is increased by 20%, while height increase 10%, then the percentage increase in the volume of the cylinder

(C) If each edge of a cube is increased by 20%, then the percentage increase in its surface area is:

(D) If the radius of a sphere is increased by 10%, then the percentage increase in its volume is:

Choose the correct order:

Solution

✅ Correct Option: 3

(A) Cube Volume - Edge increased by 20%

Original edge = aa

Volume of cube = a3a^3

New edge = a+0.2aa + 0.2a

=1.2a= 1.2a

Original volume = a3a^3

New volume = (1.2a)3(1.2a)^3

=1.728a3= 1.728a^3

Increase = 1.728a3−a31.728a^3 - a^3

=0.728a3= 0.728a^3

Percentage increase = 0.728a3a3×100\dfrac{0.728a^3}{a^3} \times 100

=72.8%= 72.8\%


(B) Cylinder Volume - Radius increased by 20%, Height increased by 10%

Original radius = rr, height = hh

Volume of cylinder = πr2h\pi r^2h

New radius = 1.2r1.2r

New height = 1.1h1.1h

Original volume = πr2h\pi r^2h

New volume = π(1.2r)2(1.1h)\pi(1.2r)^2(1.1h)

=π×1.44r2×1.1h= \pi \times 1.44r^2 \times 1.1h

=1.584πr2h= 1.584\pi r^2h

Increase = 1.584πr2h−πr2h1.584\pi r^2h - \pi r^2h

=0.584πr2h= 0.584\pi r^2h

Percentage increase = 0.584πr2hπr2h×100\dfrac{0.584\pi r^2h}{\pi r^2h} \times 100

=58.4%= 58.4\%


(C) Cube Surface Area - Edge increased by 20%

Surface area of cube = 6a26a^2

New edge = 1.2a1.2a

Original surface area = 6a26a^2

New surface area = 6(1.2a)26(1.2a)^2

=6×1.44a2= 6 \times 1.44a^2

=8.64a2= 8.64a^2

Increase = 8.64a2−6a28.64a^2 - 6a^2

=2.64a2= 2.64a^2

Percentage increase = 2.64a26a2×100\dfrac{2.64a^2}{6a^2} \times 100

=44%= 44\%


(D) Sphere Volume - Radius increased by 10%

Volume of sphere = 43πr3\dfrac{4}{3}\pi r^3

New radius = 1.1r1.1r

Original volume = 43πr3\dfrac{4}{3}\pi r^3

New volume = 43π(1.1r)3\dfrac{4}{3}\pi(1.1r)^3

=43π×1.331r3= \dfrac{4}{3}\pi \times 1.331r^3

=1.331×43πr3= 1.331 \times \dfrac{4}{3}\pi r^3

Percentage increase = (1.331−1)×100(1.331 - 1) \times 100

=33.1%= 33.1\%


Summary of Results:

(A) Cube Volume: 72.8%72.8\%

(B) Cylinder Volume: 58.4%58.4\%

(C) Cube Surface Area: 44%44\%

(D) Sphere Volume: 33.1%33.1\%


Arranging in increasing order:

33.1%<44%<58.4%<72.8%33.1\% < 44\% < 58.4\% < 72.8\%

Therefore: (D), (C), (B), (A)

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