traffic control system ,CAST STUDY  solution

 Read the case gkten below and answer the questions giaen at the end

7.To determine the effectiveness of a new traffic control system, the number of accidents that occurred aI 12 dangerous intersections during four weeks before and four weeks after the installation of the new system was observed, and the following data was obtained :

Use the paired-sample sign test at cr : 0'05 level of significance to test the null hypothesis that the new traffic control system is as effective as the earlier system.