⚡ Build the skills to land top-paying quant jobs. Offer ends in --d --h --m --s-- days -- hours -- minutes -- seconds.
⚡ Build the skills to land top-paying quant jobs. Offer ends in 18d 19h 45m 31s18 days 19 hours 45 minutes 31 seconds.
You are given an urn with balls ( black and white). You draw balls from the urn one by one, without replacement, until all the balls are out. A black ball followed by a white one, or a white ball followed by a black one, is called a "colour change". What is the expected number of colour changes when the balls are drawn in uniformly random order?