Chemical Kinetics

$\mathrm{X} \rightarrow 2 \mathrm{Y}$ is a first order reaction where $1.0 \mathrm{~mol} / \mathrm{L}$ of the reactant yields $0.4 \mathrm{~mol} / \mathrm{L}$ of Y in 200 minutes. Calculate the half-life period of the reaction in minutes.