In Testing Denote the Two Population Proportions, the Following Summary Statistics Are

Short Answer

In testing $H _ { 0 } : p _ { 1 } - p _ { 2 } = 0 \text { versus } H _ { \text {at } } : p _ { 1 } - p _ { 2 } > 0 \text { where } p _ { 1 } \text { and } p _ { 2 }$ denote the two population proportions, the following summary statistics are given: m = 400, x = 140, n = 500 and y = 160. Then the value of the test statistic is z = __________.