Let A, B, and C be three events. Show that exactly two of these events will occur with probability P (AB) + P (AC) + P (BC) 3P (ABC).

Section - 9.3 Comparison of Two population Means: Paired (Dependent) Samples Con▯dence Intervals for the di▯erence between Two Means: Paired Samples ▯ ▯ d ▯ t pd ▯=2 n where there are n pairs, d is the mean add s the standard deviation of their di▯erences. The number of degrees of freedom is df = n ▯ 1 The population of di▯erences must be normally distributed. Standardized test statistic for tests concerning the di▯erence between two means: paired data d ▯ D0 T = p sd= n ▯ where there ar