Zend certified PHP/Magento developer

What is the correct way to slow down a video 3X? [duplicate]

I have recorded a University lecture via a screen capture, in order to do it in a timely manner, I sped up the video in my browser 3X times using the extension Video Speed Controller.

Now in MPV I want to slow down the video by a factor of 3X times. I mess with video speed all the time in MPV, up to now though, I have only ever increased a videos speed.

I have tried doing some maths to figure it out but it does not make sense. if speed=1 is the normal rate, then is speed=0.50 1x slower? If so then I am not sure I how can slow down two more times from speed=0.50.

Even if I were to correct the playback speed, I suspect it will not be identical to the original video. I accept that, its just a dry lecture. I just want to get it as close as possible.

Any help would be greatly appreciated!