Answer:
62.6%
Explanation:
To convert the mountain height to miles, we divide its height in feet by the number of feet per mile. We want the fraction of that represented by 3 miles, so ...
(3 mi)/((25,289 ft)/(5,280 ft/mi)) × 100%
= 3(5280)/25289 × 100% ≈ 62.6%
If you climbed 62.6% of the mountain's height, you would be 3 miles above sea level.