To calculate the height of Mt. Everest, we add the height of Denali (20,000 ft, or \(2 \times 10^4\) ft) to the additional height of Mt. Everest over Denali, which is given as about \(9 \times 10^3\) ft.
So, we perform the following addition:
\[ \text{Height of Mt. Everest} = \text{Height of Denali} + \text{Additional Height} \]
Converting Denali's height to scientific notation:
\[ 20,000 \text{ ft} = 2 \times 10^4 \text{ ft} \]
Adding the height of Denali and the additional height:
\[ 2 \times 10^4 + 9 \times 10^3 \]
First, we convert \(9 \times 10^3\) to have the same exponent as \(2 \times 10^4\):
\[ 9 \times 10^3 = 0.9 \times 10^4 \]
Now we can add them together:
\[ 2 \times 10^4 + 0.9 \times 10^4 = (2 + 0.9) \times 10^4 = 2.9 \times 10^4 \]
Therefore, the height of Mt. Everest is:
\[ \text{Height of Mt. Everest} \approx 2.9 \times 10^4 \text{ ft} \]
The correct answer is:
2.9×10^4 ft.