Please help with both of these

Problem $2$

The mean mixing time in bioreactor has been estimated to be inversely proportional to the

agitation rate when the bioreactor is scaled geometrically. If the power input per unit volume is to

be kept constant, what will happen to the mean mixing time when scaling up$?$ If the mean

mixing time is to be kept constant in scaling up$,$ what will happen to the power input per unit

volume and maximal velocity $($or tip speed$)$

Problem $3$

A stirred$-$tank bioreactor is $12m$ in height and $3m$ in diameter. Two Rushton turbines, with a

diameter of $0\mathrm{.}45$ of the tank diameter, are installed. The agitation rate is $100rpm.$ The working

volume reaches $70\%$ of the tank height. You are designing a scaled$-$down version using a $200-L$

reactor that is geometrically similar. What should be the operating conditions if you are to keep

the power$-$per$-$unit volume constant or to keep the tip speed constant?