Ahot-air balloon was decommissioned after a successful flight by letting the 3000 m^3 of air in it leak out. the loss in the volume of air in the balloon was exponential, decreasing at x percent per minute. if there was 1626 m^3 of air in the balloon 15 minutes after it began to be decommissioned, at what percent per minute to the nearest percent did the balloon lose air?
a) 1%
b) 2%
c) 3%
d) 4%

For the first minute, the new volume of air is 3000 x because X% volume of air is lost every minute.What would've happened is a total of 3000 x  would've been lost.

thus, what we have so far is:
3000 x  = 1626
 = 


which is same as:
(rounded)
x 100
100 - X = 95.999
-X = 95.999 - 100
X ≈ 4

Therefore, 4% of air was lost from the balloon every minute.

BTW 
The reason I did  was because in multiplications, the order doesn't matter, so instead of doing

15 times, I just merged them into that equation

UPDATED sorry forgot some steps...