The periodic times of the planet Jupiter’s satellites, Ganymede and Callisto, have been observed to be 7.15 days and 16.69 days, respectively. Knowing that the mass of Jupiter is 319 times that of the earth and that the orbits of the two satellites are circular, determine

(a) The radius of the orbit of Ganymede,

(b) The velocity with which Callisto describes its orbit. Give the answers in SI units. (The periodic time of a satellite is the time it requires to complete one full revolution about the planet.)