oldeng

If we call as R(h), cone radius al a function of height h, then
R(h)= 4 -h/3  When cylider touchs the cone:

r = 4 - h/3 (1)

Area  A of base cylinder is:

A =¶ *r²  and h by (1) is h = (12 -3r)

Cylinder volme is:

V = A *h = ¶ *r² *(12 -3r)= ¶*(12 r^{2 -} 3r³⁾ 

In your answer ¶ is missing

Regards

Always the pyramid volume is:

V= (1/3)*A *h where A is the base area and h is the height

V = (1/3)*14 *35 =163.33 units