6.1 & 6.2
Properties of Normal Curve
2. The curve is symmetrical about a vertical line through u.
3. The curve approaches the horizontal axis but never touches or crosses it.
4. The inflection (transition) points between cupping upward and downward occur aboce u +0 and u - o.
5. The area under the entire curve is 1.
approximately 68% of the data values will lie within 1 standard deviation on each side of the mean.
approximately 98% of the data values will lie within 2 standard deviations on each side of the mean.
approximately 99.7% of the data values will lie within 3 standard deviations on each side of the mean.
1. find the mean u and standard deviation o of the x distribution by using past data from period during which the process was in control or
b. using specified target values for u and o.
2. create a graph in which the vertical axis represents x values and the horizontal axis represents time.
3. draw a horizontal line at height u and horizontal, dashed control-limit lines at u + 20 and u + 30.
4. plot the variable x on the graph in time sequence order. use line segments to connect the points in time sequence order.