To find the height of Mt. Everest, we start with the height of Denali, which is approximately 20,000 ft (or \(2.0 \times 10^4\) ft). Since Mt. Everest is about \(9 \times 10^3\) ft higher than Denali, we need to add this to Denali's height:
\[ \text{Height of Mt. Everest} = \text{Height of Denali} + \text{Height increase} \] \[ \text{Height of Mt. Everest} = 20,000 , \text{ft} + 9,000 , \text{ft} \] In scientific notation, this is: \[ \text{Height of Mt. Everest} = 2.0 \times 10^4 , \text{ft} + 9.0 \times 10^3 , \text{ft} \]
We can convert \(9,000\) ft into scientific notation: \[ 9,000 , \text{ft} = 9.0 \times 10^3 , \text{ft} \]
Now, we rewrite \(20,000\) ft in terms of powers of ten: \[ 2.0 \times 10^4 , \text{ft} + 0.9 \times 10^4 , \text{ft} = (2.0 + 0.9) \times 10^4 = 2.9 \times 10^4, \text{ft} \]
Thus, the height of Mt. Everest is approximately: \[ \boxed{2.9 \times 10^4} , \text{ft} \]