thank you so much! i think i arrived at the right answer
0.55 (5,000,000) = 2,750,000
2,750,000 = 5,000,000e ^ (-k)(1)
Divide 5,000,000 on both sides therefore i got:
.55 = e ^ (-k)(1)
ln(.55) = lne ^ -1k
** ln(e^x) = x --> lne ^ -1k = -1k
ln(.55) = -1k
_____ ___
-1 -1
ln(.55) / (-1) = .5978
k = .5978
Q = ae ^ (-k)(t) (For continuous decay --which is why we use -k and not k which is used for continuous growth)
1000 = 5,000,000e ^ (-.5978)(t)
Divide 5,000,000 by both sides =
.0002 = e ^ -.5978t
ln(.0002) = lne ^ -.5978t
ln(.0002) = -.5978t
_______ ______
-.5978 -.5978
ln(.0002) / (-.5978) = approx. 14.2 minutes
t = approx. 14.2 minutes
(i hope i did that correctly
)