Suppose a merry-go-round is spinning once every three seconds if a point on the outside edge has a speed of 12.56 ft./s what is the radius of the merry-go-round

20. 
let the point be point P. point P travels linear speed = 12.56 ft/sec 
in three sec, or one revolution, it travels 

12.56 ft/sec times 3 sec= ......feet, which is the perimater of the imaginary circle. then use the perimter of circle formula, solve for radius