The marks obtained by four students in Mathematics and Hindi are shown in the table below. (The maximum marks for each subject are 100.)
| Student/Subject | Mathematics | Hindi |
| P | 84 | 88 |
| Q | 90 | 74 |
| R | 92 | 70 |
| S | 70 | 68 |
What is the product of the average marks obtained by all the four students in Mathematics and those in Hindi?