Intro Stats, Lect 9B, Discrete & Continuous Random Variables, Means and Standard Deviations

(0:00) Find a probability by calculating the area under a triangular distribution.
(3:32) With random continuous variables like this, the "strictness" of the inequalities doesn't matter (since lines have no areas). It does matter for discrete random variables.
(4:14) Normal distribution example (hummingbird weights).
(5:40) Use probability notation and convert to z scores within the probability notation.
(7:27) Use a standard Normal table to find the probability.
(9:23) Summary of discrete and continuous random variables.
(11:25) Summary of our main use of random variables: sample statistics are random variables and their sampling distributions are used to find probabilities related to them.
(14:30) Formula for the mean of a discrete random variable (with finitely many values) and a summary of how to use it with a table.
(17:14) Formulas for the variance and standard deviation of a discrete random variable (with finitely many values).
(20:00) Manufacturing costs example (based on # of weeks for developing product specifications and # of weeks for designing the manufacturing process).
(23:23) Relate the mean of the combined variable to the means of its "parts".
(24:23) Use a spreadsheet to find the means of the parts.