A long solenoid with 1000 turns /m has a core material with relative permeability 500 and volume `10^(3)cm^(3)` .If the core material is another material having relative permeability of 750 with same volume maintaining same current of 0.75 A in the solenoid, the fractional change in the magne tic moment of the core would be approimately `((x)/(499))` Find the value of x.