Question 1080735
4.25=11e^(-24k) ,where k is in minutes
0.3864=e^(-24k)
ln both sides, then divide by -24 and finally round
k=0.0396
now use that for 2mg
2=11*e-(kt), exponent is 0.0396t
0.182=e-(0.0396 t)
ln of both sides then divide by -0.0396, rounding at end.  I would estimate the answer to be between 24 and 48 minutes, since after 24 less than half remained.
t=43.05 minutes. When one guesses a range before solving, and has a decent guess, this serves as a good check.