[填空题]
A heart pacemaker is9;5i 3rh .ccninm 6tcf designed to operate at 72 beatvziykdu((u9g/p1jz tqh * l8q nx5w1 .s/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$
