Maths

The side of a cube is 15cm long.If each side of the cube increases by 20%,find the percentage increase in its volume.

Volume of the original cube
= (15 cm)(15 cm)(15 cm)
= 15³ cm³

New cube length
= 15 * (1+20%)
= 15 * 120%
= 15 * 1.2 cm

Volume of the new cube
= (15 * 1.2 cm)(15 * 1.2 cm)(15 * 1.2 cm)
= (15)(15)(15)(1.2)(1.2)(1.2) cm³
= (15³)(1.2³) cm³
= (15³)(1.728) cm³

Percentage increase in volume
= [(15³)(1.728) - 15³]/15³ * 100%
= (1.728-1) * 100%
= 0.728 * 100%
= 72.8%

So the percentage increase in volume is 72.8%.

72.8%

[15 X (1+20%) X 15 X (1+20%) X 15 X (1+20%) - 15 X 15 X 15 ] then divided by (15 X 15 X 15) then times 100%