# Find the rate of change midel of N per unit change of t--> dN/dt

*label*Mathematics

*timer*Asked: Mar 25th, 2015

**Question description**

The total number of bacteria(in thousands) present, N, in a culture is given by N(t)=3t(4t+9)^(1/2)+10, where t is time in hours after the beginning of the experiment.

Also, I need help on a sentence of interpretation for when 6 hours have passed.