1. **State the problem:** Calculate the sum of $2.8 \times 10^{6}$ and $11 \times 10^{6}$ and express the answer in scientific notation. 2. **Formula and rules:** When adding numbers in scientific notation with the same power of 10, add the coefficients and keep the power of 10 the same. 3. **Calculate the sum:** $$2.8 \times 10^{6} + 11 \times 10^{6} = (2.8 + 11) \times 10^{6}$$ 4. **Add the coefficients:** $$2.8 + 11 = 13.8$$ 5. **Express in scientific notation:** Since $13.8$ is not between 1 and 10, rewrite it as: $$13.8 = 1.38 \times 10^{1}$$ 6. **Combine powers of 10:** $$13.8 \times 10^{6} = 1.38 \times 10^{1} \times 10^{6} = 1.38 \times 10^{7}$$ **Final answer:** $$\boxed{1.38 \times 10^{7}}$$