Calculate Remaining Anesthetic Time: Mass Flow Rate Question

[jmine]

Homework Statement

A patient, on an anesthetic, is hooked up with only 18 mg of the anesthetic remaining. If the current flow is 12 mg/h and the dentist needs to increase the flow to 20.0 mg/h within two minutes, then how long will it take for the anesthetic to run out?

Homework Equations

mfr = Mass flow rate
mfr = ∆m/∆t

amfr = Acceleration Mass flow rate
amfr = ∆mfr/∆t[/B]

The Attempt at a Solution

[/B]

 

[tommyxu3]

My opinions for reference:
You should pay attention to the $20\text{mg}/\text{h}$ increase and how it increases. Then can see the consumption during these two minutes.

 

[billy_joule]

Is that exactly as stated in the book? It's a little ambiguous...
I'd guess it's attempting to say:

A patient, on an anesthetic, is hooked up with only 18 mg of the anesthetic remaining. the initial flow is 12 mg/h, the dentist gradually increases the flow to 20.0 mg/h over a period of two minutes, then how long will it take for the anesthetic to run out?

 

[haruspex]

Is that exactly as stated in the book? It's a little ambiguous...
I'd guess it's attempting to say:

A patient, on an anesthetic, is hooked up with only 18 mg of the anesthetic remaining. the initial flow is 12 mg/h, the dentist gradually increases the flow to 20.0 mg/h over a period of two minutes, then how long will it take for the anesthetic to run out?

Possibly, but to me it sounds more that after two minutes the flow will increase in one step to 20mg/h. Your interpretation has the merit of making the question more interesting.
Is it only the interpretation that's stopping you? If there's more help needed, you must post an attempt.