Power factor correction help

[malcoa]

Hi guys
i need a bit of tec help, the question is as follows.

For a given final power factor (usually 0.9) and initial power factor and load kilowatts, produce a formula that will give the size of power factor correction capacitor required. (50hz supply)

trawled google and i cant fathom this answer.

hope you clever sods might know something about this

thanks