Different formulas
The answer to Systems question 55 will be 86.7% if you use the formula in this lecture, and 86.2% if you use the technique in the books. The difference is that the method in the books does not take into account the secondary internal reflection that will add slightly to the final transmission number.
The total transmission answer to Formulas will be
- 92.4%
- 90.2%
- 88.4%
Same reason for the differences compared to the answers in the book.