Calculating resistance of pacemaker

[hmiller89]

Homework Statement

A pacemaker sends a pulse to a patient's heart every time the capacitor in the pacemaker charges toa voltage of 0.25 V. It is desired that the patient receive 75 pulses per minute. Given that the capacitance of the pacemaker is 110 uF and that the battery has a voltage of 9.0 V, what value should the resistance have?

Homework Equations

What value is the resistance?

The Attempt at a Solution

 

[zhermes]

What are the equations involving a charging capacitor?
(hint: its not "what value is the resistance").