Aconsumer advocacy group wants to determine whether there is a difference between the proportions of the two leading automobile models that need major repairs (more than $500) within two years of their purchase. a sample of 400 two-year owners of model 1 is contacted, and a sample of 500 two-year owners of model 2 is contacted. the numbers x1 and x2 of owners who report that their cars needed major repairs within the first two years are 53 and 78, respectively. what is the p-value of the appropriate test of hypotheses. also calculate the z-score and p-value. show your work.