A random sample of 160 car purchases are selected and categorized by age. The results are listed below. The age distribution of drivers for the given categories is 18% for the under 26 group, 39% for the 26 dash 45 group, 31% for the 45-65 group, and 12% for the group over 65. Find the critical value chi Subscript alpha Superscript 2 to test the claim that all ages have purchase rates proportional to their driving rates. Use alpha equals 0.05 .