What is the time constant of a circuit having a 220 microfarad capacitor in series with a 470 kilohm resistor?

The time constant τ represents the time it takes for an RC circuit to charge to 63.2% or discharge to 36.8%. It is found by multiplying the resistance by the capacitance (τ = R × C). Before multiplying, you must convert the parameters into standard units of ohms and farads. The resistance of 470 kilohms translates to 470,000 ohms. The capacitance of 220 microfarads translates to 0.000220 farads. Multiplying these standard units together gives 470,000 × 0.000220 = 103.4 seconds. The closest correct option is 103 seconds.