Pyramid volume

[ss_0001]

Hi,

A pyramid consists of cubes with a side length of 2cm. What volume has the pyramid if it has 10 cube layers?

I used the formula 1/3 (base area) x height.

Eg 1/3 (20 x 20) x 20
= 2666.67

But the answer is shown as 3080(?) Any ideas what I did wrong?

thanks.

 

[tkhunny]

Are you sure we have a full description? Are the sides smooth? Does it shrink on the way up?

Layer 1: 20 cm * 20 cm * 2 cm
Layer 2: 18 cm * 18 cm * 2 cm
etc.

I get 3080 cm^3

Your pyramid formula should be considered a rough approximation. It cuts off the cubes' corners.

 

[tkhunny]

I did explain. You have eight more layers to go.

 

[ss_0001]

thanks, I get it now.

I never thought of doing it that way....

 

[tkhunny]

No other way to proceed. We're stacking blocks! Good work.