Question

В домашней библиотеке 90 учебников, что составляет 30% всех книг в ней. Из всех книг домашней библиотеки 60%- книги по художественной литературе, а остальные-справочники и словари. Сколько справочников и словарей в домашней библиотеке?

Answer 1

100% это все книги - неизвестно

30% это учебники - 90книг

60% это книги по художественной литературе - неизвестно

100-30-60=10 % - это справочники и словари - неизвестно

решаем:

90 учебников - это 30%

тогда 100% всех книг - это 90 : 30 *100 = 300 книг в домашней библиотеке

180 книг по художественной литературе - 60%

100 % (всех книг) - 30 % (учебников) - 60% (худ.литературе) = 10% (справочники и словари)

10% = 300 * 10 : 100 = 30 книг - это справочники и словари

(300-90-180=30)

 

Ответ:30 книг 10% справочники и словари.

 

 

 

Answer 2

1)сколько всего книг в библиотеке?

90:0,3=300 книг

2)сколько по художественной литературе?

300*0,6=180 книг

3)сколько справочников и словарей?

300-90-180=30 книг

Answer 3

Calculation of the Number of Reference Books and Dictionaries in the Home Library

To determine the number of reference books and dictionaries in the home library, we need to use the information provided.

According to the given information: - The home library contains 90 textbooks, which make up 30% of all the books in the library. - 60% of all the books in the library are books on fiction literature. - The remaining books in the library are reference books and dictionaries.

To calculate the number of reference books and dictionaries, we can follow these steps:

1. Calculate the total number of books in the home library: - Since the textbooks make up 30% of all the books, we can calculate the total number of books using the formula: total number of books = number of textbooks / (percentage of textbooks / 100). - Plugging in the values, we get: total number of books = 90 / (30 / 100) = 90 / 0.3 = 300.

2. Calculate the number of books on fiction literature: - Since these books make up 60% of all the books, we can calculate the number of books on fiction literature using the formula: number of books on fiction literature = total number of books * (percentage of fiction literature / 100). - Plugging in the values, we get: number of books on fiction literature = 300 * (60 / 100) = 300 * 0.6 = 180.

3. Calculate the number of reference books and dictionaries: - The remaining books in the library are reference books and dictionaries, so we can calculate their number using the formula: number of reference books and dictionaries = total number of books - number of books on fiction literature. - Plugging in the values, we get: number of reference books and dictionaries = 300 - 180 = 120.

Therefore, there are 120 reference books and dictionaries in the home library.