First, we determine the volume of the trunk by finding first the radius from the circumference through the equation,
                                                           C = 2πr
                                                           r = C/2π
Substituting the known values,
                                                           r = 4.5/2π = 0.716 m
Then, we calculate for the volume through the equation,
                                                           V = πr2h
                                               V = π(0.716 m)2(8m) = 12.9 m3
Multiplying the calculated value to the density will give the mass as,
                                               Mass = (12.9 m3)(752 kg/m3) = 9699.36 kg