31.

Sum of the first 20 terms of an AP is -240, and its first term is 7. Find its 24^th term.

A solid is in the shape of a cone standing on a hemisphere with both their radii being equal to 7 cm and the height of the cone is equal to its diameter. Find the volume of the solid.

$\left[\mathrm{Use} \mathrm{\pi }= \frac{22}{7}\right]$