To find the expected number of deer in an area of 300 square miles, you can use the deer population density from the sampled area.
The deer population density is calculated as follows:
\[ \text{Density} = \frac{\text{Number of Deer}}{\text{Area}} = \frac{200 \text{ deer}}{10 \text{ square miles}} = 20 \text{ deer/square mile} \]
Now, to find how many deer are expected in 300 square miles:
\[ \text{Expected number of deer} = \text{Density} \times \text{Area} = 20 \text{ deer/square mile} \times 300 \text{ square miles} = 6,000 \text{ deer} \]
So the scientist can expect to find 6,000 deer in an area of 300 square miles.