What is the equivalent resistance of the dielectric?

Dielectric materials used in the manufacture of capacitors are characterized by conductivities that are small but not zero. Therefore, a charged capacitor slowly loses its charge by "leaking" across the dielectric. If a certain 5.40micr-F capacitor leaks charge such that the potential difference decreases to half its initial value in 4.30s, what is the equivalent resistance of the dielectric? Round answer to 3sig.figs. in M-ohms.