The article “Case Study Based Instruction of DOE and SPC” (J. Brady and T. Allen, The American Statistician, 2002:312–315) describes an effort by an engineering team to reduce the defect rate in the manufacture of a certain printed circuit board. The team decided to reconfigure the transistor heat sink. A total of 1500 boards were produced the week before the reconfiguration was implemented, and 345 of these were defective. A total of 1500 boards were produced the week after reconfiguration, and 195 of these were defective. Find a 95% confidence interval for the decrease in the defective rate after the reconfiguration.