$10-$m$3$ reactor $($D$=2\mathrm{.}0-$m$)$ has a $4-$blade $45$ pitched impeller with a diameter of $1-$m and rotates at $100-$RPM$.$ It is proposed that the impeller be replaced with a similar but larger one $1\mathrm{.}2-$m in diameter. No change to number of blades, pitch, or W$/$d ratio. What is the percentage change in power input that would be needed with the new impeller?