1. A solid cylinder has total surface area of 4158 cm². The curved surface area is one-third of its total surface area. What is the radius of the base of this cylinder? [Use \(\pi = {22 \over 7}\)]

2. If the base radius and height of a right circular cone are 5 cm and 12 cm respectively, then its slant height is ______.

3. Find the least square number which is exactly divisible by 4, 6, 12 and 25.

4. A can do a piece of work in 4 days, and B can do the same work in 8 days. With the help of T, they finished the work in 2 days. T can do the work in how many days, working alone?