The general equation for the forces acting on the passengers at the topmost point of the ferris wheel is

where
mg is the weight of the passengers
R is the normal reaction of the cabin

is the centripetal force
In order to feel weightless, the normal reaction felt by the passengers should be zero. Therefore, the equation becomes:

or

where

is the angular frequency of the wheel and r is its radius. Since we know its radius,

we can calculate the angular frequency:

From which we find the frequency at which the ferris wheel should rotate:

This is the number of revolutions per second, so the number of revolutions per minute will be