How do you derive these? Edit: probability for daily event, see here: https://en.m.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule https://en.m.wikipedia.or

How do you derive these? Edit: probability for daily event, see here: https://en.m.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule https://en.m.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_r...