The difference between the boiling point and freezing point of an aqueous solution containing sucrose (mol wt. ${ = 342\;g\;{\rm{mo}}{{\rm{l}}^{ - 1}}}$) in 100 g of water is $105.0^\circ C$. If ${K_f}\;{\rm{and}}\;{K_b}$ of water are 1.86 and $0.51\;K\;kg\;{\rm{mo}}{{\rm{l}}^{ - 1}}$ respectively, the weight of sucrose in the solution is about