Probability and SLAs, Part 1
I recorded this quickly today as a refresher on probability. There are some links in the slides that I go through that will be in the final slide deck from this whole discussion. Once I have posted all the parts of this series, I'll post the slide deck. Until then:
Error in the video:
In the video, I show some probabilities of drawing 2 Red Kings in a row from a deck of cards. There's a typo in the video at that point where I fix it, but I think the probability column for that still deserves some attention.
The probability of drawing a Red King is 2/52 each time, if you replace the card in between draws. That's why those draws are INDEPENDENT events. The the probability of this actually happening is 2/52 * 2/52 = 4/2704 = 0.0015.
If the card is not replaced, the second draw is DEPENDENT of the first draw. The probability of drawing a Red King the first time is still 2/52, but for the second draw, there is only 1 Red King left and only 51 cards, so that probability is 1/51. The probability of both happening, then, is 2/52*1/51 = 2/2652 = 0.00074. Not so good!