Question

Two square based pyramids are joined, total volume is 2700mm, perpendicular height of top pyramid is 16mm, perpendicular height of bottom pyramid is 20mm, length and width of joint base area both x, find x. Please help me

Answer 1

Answer: 15 m

Explanation:

Given

Total volume of the combined pyramid is
`V=2700\ mm^3`

Height of top and bottom pyramid is

`h_t=16\ mm`

`h_b=20\ mm`

If the base has a side length of x, its area must be
`x^2`

Volume of square prism is given by

`\Rightarrow V=(1)/(3)Bh\quad [\text{B=base area}]\\\\\text{Total volume will be the sum of the two pyramids}\\\\\Rightarrow 2700=(1)/(3)* x^2* 16+(1)/(3)* x^2* 20\\\\\Rightarrow 2700=(1)/(3)* x^2* (16+20)\\\\\Rightarrow x^2=225\\\Rightarrow x=15\ mm`

Thus, the value of
`x` is 15 m.