The answer 0.12 represents the portion of books in the library that are how-to books on electronics.
This can be understood as follows:
- The calculation 0.3 (how-to books) × 0.4 (how-to books on electronics) gives us 0.12, which indicates that 12% of the total books in the library are specifically how-to books about electronics.
Thus, the correct interpretation from your options would be:
the portion of the books in the library that are how-to books on electronics.