QMS 102 Lecture Notes - Lecture 9: Formula 4, Standard Deviation, Probability Distribution

• School: Ryerson University
• Department: Quantitative Methods
• Course: QMS 102
• Professor: Nursel Ruzgar

Document Summary

2: in symmetrical, mean and median are the same, the values tend to cluster around mean and median (bell shaped, ex. 72% of the values must be found within +2 standard deviations from mean. 3: the cumulative standardized normal table in the textbook gives the probability of less than a desired value of z, ex. General procedure for finding normal probabilities: draw the normal curve for the problem in terms of x, translate x-values into z-values, use the standardized normal table. Inverse normal: given normal probability find the x value: steps to find x value for known probability, find the z-value for the known probability, convert to x units using the formula, x = mean + z(deviation, ex. Let x represent time (in secs. ) to download an image from the internet: suppose x is normal with mean 18 and deviation 5, find x such that 20% of download times are less than x, 1.