area of cylinder curved surface= 2.pi.r.h;
area of one end = pi.r²
h = height of cylinder
r = radius of base.
2.pi.r.(50) + pi.r² = 3000.
So: pi.r² + 100.pi.r - 3000 = 0
its a quardatic equation
The value of r that is > 0 and that satisfies that equation is r = 8.778.
So radius = 8.778 cm
hope this helps