[填空题]
A heart pacemaker is designedtlsbmo0m 39t 9 to 0-7j jj hvbu:z)1ry lyoperate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum? $ \times10^{-5 }\;\Omega$
