To find the area of a Canadian football field, we start with the area of an American football field, which is given as \( 6.4 \times 10^3 \) square yards.
The Canadian football field is \( 3,350 \) square yards larger than the American football field.
We first need to express \( 3,350 \) in scientific notation:
\[ 3,350 = 3.35 \times 10^3 \]
Next, we add this to the area of the American football field:
\[ \text{Area of Canadian football field} = (6.4 \times 10^3) + (3.35 \times 10^3) \]
To add these, we can combine the coefficients since they have the same exponent:
\[ = (6.4 + 3.35) \times 10^3 \]
Calculating the sum of the coefficients:
\[ 6.4 + 3.35 = 9.75 \]
Thus, the area of the Canadian football field is:
\[ 9.75 \times 10^3 \text{ square yards} \]
Therefore, the answer in scientific notation to 2 decimal places is:
\[ \boxed{9.75 \times 10^3} \text{ square yards} \]