In order to calculate the number of protozoa after 2 days (that is, 48 hours), let's use t = 48 in the function p(t) and calculate its value:
[tex]\begin{gathered} p(t)+0.02t^4+0.3t^3+7t^2 \\ p(48)=0.02\cdot48^4+0.3\cdot48^3+7\cdot48^2 \\ p(48)=0.02\cdot5308416+0.3\cdot110592+7\cdot2304 \\ p(48)=106168.32+33177.6+16128 \\ p(48)=155473.92 \end{gathered}[/tex]Rounding to the nearest whole number, the number of protozoa is 155474.