Chapter 15 - Electric Charge, Forces, and Fields - Learning Path Questions and Exercises - Conceptual Questions - Page 555: 8

The force would become 6 times the initial force i.e. $6F$

We know that, $F=k\frac{q_{1}.q_{2}}{r^{2}}$ When the charge of one was doubled and that of the other was tripled, then new force $F_{1}=k\frac{2q_{1}.3q_{2}}{r^{2}}=6F$ The force would become 6 times the initial force.