Given, P′N2+P′H2O=760mm
After the use of drying agent, H2Ov are absorbed
P′N2=745mm
P′H2O=760−745=15mm
P′N2=PM× mole fraction of N2
mole fraction of N2=PN2PM=745760=0.9803
% mole fraction of N2=98.03%
% mole fraction of H2O=1.97%
So, nearest integer value is 98.