Answer:
785 ft
Step-by-step explanation:
The increases in height can be modeled by a geometric series with first term 250 and common ratio 0.7. The sum of n terms of such a series is given by ...
Sn = 250(1 -0.7^n)/(1 -0.7)
Then the 8th term, the height after 8 minutes, will be ...
S8 = 250(1 -.057648)/(0.3) ≈ 785.3 ft
After 8 minutes, the balloon will be about 785 feet high.
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If it continues like that, its ultimate height will be about 833.3 feet.
