How-to books make up 0.3 of the books in the school library. Of these how-to books, 0.2 deal with carpentry and 0.4 deal with electronics.
To find how many books in the school library are how-to books, you can multiply the total number of books by the percentage of how-to books:
Total number of books in the library * Percentage of how-to books
Let's assume there are 100 books in the school library.
Total number of books in the library = 100
Percentage of how-to books = 0.3
Number of how-to books = 100 * 0.3 = 30
Out of these how-to books, 0.2 deal with carpentry.
Number of carpentry books = 30 * 0.2 = 6
And 0.4 deal with electronics.
Number of electronics books = 30 * 0.4 = 12
So, there are 6 carpentry books and 12 electronics books in the school library.
To determine the fraction of how-to books in the school library, we need to add the fractions of books dealing with carpentry and electronics.
Fraction of carpentry books = 0.3 (how-to books) * 0.2 (carpentry books) = 0.06
Fraction of electronics books = 0.3 (how-to books) * 0.4 (electronics books) = 0.12
The total fraction of how-to books in the school library is the sum of these fractions:
Fraction of how-to books = 0.06 (carpentry books) + 0.12 (electronics books) = 0.18
Therefore, how-to books make up 0.18 of the books in the school library.
To find out the number of how-to books in the school library, you need to know the total number of books in the library.
Let's assume the total number of books in the school library is "x".
According to the given information, how-to books make up 0.3 (or 30%) of the books in the library. So, the number of how-to books can be found by multiplying the total number of books by 0.3:
Number of how-to books = 0.3 * x
Out of these how-to books, 0.2 (or 20%) deal with carpentry. So, the number of how-to carpentry books can be found by multiplying the number of how-to books by 0.2:
Number of how-to carpentry books = 0.2 * (0.3 * x)
Similarly, 0.4 (or 40%) of the how-to books deal with electronics. So, the number of how-to electronics books can be found by multiplying the number of how-to books by 0.4:
Number of how-to electronics books = 0.4 * (0.3 * x)
You can substitute the value of "Number of how-to books" using the first equation to find the number of books in each category.