Someone answer please I would be very grateful

Answer:
Part A : 9.555 . 10^38
Part B : 7.4 . 10^-3
Step-by-step explanation:
[tex]3.9 \: . \: {10}^{33} . \: 2.45 \: . \: {10}^{5} \\ 3.9 \: . \: 2.45 \: . \: {10}^{33 + 5} \\ 9.555 \: . \: {10}^{38} \\ [/tex]
[tex]7.4 \: . \: {10}^{ - 3}mm \\ 7.4 \: . \: \frac{1}{ {10}^{3} } \\ 0.0074mm[/tex]
[tex]7.4 \: . \: {10}^{3}mm \\ 7.4 \: . \: 1000 \\ 7400mm[/tex]
A blood cell is too small. So the more reasonable measurement is 0.0074mm.