1. The sample mean x of observations x1, x2,..., x is given by: x 2. Sample median: 21 (n+1)th ordered values x= (average of (4) and (+1)" ordered values 4 3. Sample variance: $2(x-x)x-(Ex) n-1 n-1 when n is odd when n is even 4. Fourth spread (Interquartile range) = fs-upper fourth - lower fourth 5. Any observation farther than 1.5fs from the closest fourth is an outlier. An outlier is extreme if it is more than 3fs from the nearest fourth, and it is mild otherwise. 6. Let denote the null event. When An B=0, A and B are said to be mutually exclusive or disjoint events. 7. P(A UB) = P(A) + P(B)-P(A n B) 8. P(A) 1 P(A) 9. P(A UA') = P(S) = 1 N(A) 10. P(A) = N Number of outcomes containing A Total number of outcomes in the sample space 11. Combination: () n! k!(n-k)! P(ANB) 12. Conditional probability of A given B: P(A|B) = P(B) 13. The multiplication rule: P(A n B) = P(A|B).P(B)