Ratio of volume of a cone to the volume of a cylinder for same base radius and
same height is __________

The correct answer is: 1:3

Let us take a cylinder  of height "h", base radius "r", and take 3 cones of height "h". Fill the cones with water and empty out one cone at a time

Each cone fills the cylinder to one-third quantity. Hence, such three cones will fill the cylinder. Thus, the volume of a cone is one-third of the volume of the cylinder.
Volume of cone = (1/3) × Volume of cylinder
= () × πr²h
= ()πr²h
So the ratio of volume of cone to the volume of cylinder is 1:3
Therefore , the correct option is b) 1:3