In a test of the effect of dampness on electric connections, 103 electric connections were tested under damp conditions and 151 were tested under dry conditions. Twenty of the damp connections failed and only 10 of the dry ones failed. Let pX represent the population proportion of damp connections that fail and let pY represent the population proportion of dry connections that fail. Find a 90% confidence interval for the difference pX−pYpX−pY. Round the answers to four decimal places.
