what percent of tire....

Question

The results of a study made as part of a performance improvement effort at a automobile manufacturing plant provided data for a sample of 500 tires. The following table contains a summary of the results for two classifications or tires (Type I/Type II of different materials and tire was good/bad)
1. What percent of the tires were good?
2. For those cases where it was classified as Type 1, what percent of the tires were good?
3. For those cases where Type II material was found, what percent of the tires were good?

                                   TYPE I           TYPE II        Total

              GOOD            380                  20              400   

               BAD              60                    40              100

               TOTAL           440                  60              500

Answer 1

1. 400/500 = 80% good tires

 

2. 380/440 = 86.4% of Type I were good  

 

3. 20/60 = 33.3% of Type II were good