Question 1144616
The exponential/decay formula is
:
A = Pe^(rt), A is the ending amount(for example: bacteria, or radioactive element), P is the beginning amount, r is the growth or decay rate, t is time, e is a constant 
:
For this problem, the units of t are hours(t = 60), at t = 0, P = 1,000
:
First, we want to find the value for r
:
2084000 = 1000 * e^(r * 60)
:
2084 = e^(r * 60)
:
take natural logarithm of both sides of =
:
60r = ln(2084)
:
r = ln(2084)/60 = 0.1274/hour
:
(a) 2000 = 1000 * e^(0.1274 * t)
:
2 = e^(0.1274t)
:
0.1274t = ln(2)
:
t = ln(2)/0.1274 = 5.44 hours
:
(b) 4000 = 1000 * e^(0.1274 * t)
:
4 = e^(0.1274 * t)
:
t = ln(4)/0.1274 = 10.88 hours
: