Question

A pyramid has a square base with sides 100 feet long. The original height was 75 feet.

but the top part of the pyramid, which was 15 feet in height, was cut off.
What percent of the original volume remains?​

Answer 1

99.2%

Explanation:

Ratio of volumes = (Ratio of sides)³

Ratio of volumes = (15/75)³

Ratio of volumes = 1/125

1/125 × 100 = 0.8% was cut off

100 - 0.8 = 99.2% remains

Answer 2

Explanation:

Step 1: Find the volume of the original pyramid

`V = a^2*(h)/(3)`

`V=(100)^2*(75)/(3)`

`V=10000*25`

`V=250000`

Step 2: Find the volume of the cut off

`V=(20)^2*(15)/(3)`

`V = 400*5`

`V=2000`

Step 3: Find the percent that still remains

`250000-2000`

`248000`

`248000 / 250000`

`0.992*100`

`99.2`

Answer: 99.2%