Pluto's orbital semi-major axis is 39.48 times larger than that of Earth. According to Kepler's third law, how long is the period of its orbit around the Sun?
When the semi-major axis a is in AU unit and the period is in Earth year, the period of any solar orbiter is a X sqrt (a). For Pluto, this is 248.065 years = (rounded to 4 sd) 248.1 years, nearly
This is only an approximation to the period, using Kepler's third (empirical) law for approximating the period..