1. You should use a site such as Stat Trek to answer this question using the binomial distribution.

The event of interest is whether a stock price goes up (a "success") or stays the same/goes down (a "failure") in a day. Say over the past few years, for the approximately 250 stock trading days per year, the price of a particular stock went up 55% of the time.

1. Over the next 30 trading days, what is the probability that the stock will go up in price in at least 20 days (ie, 20 days or more)?

How would you evaluate this probability when thinking about whether to invest in this stock? My guess is that no two answers will be the same. I just want you thinking about how to use probability estimates. A short answer is good.