Question

На первой полке 9 книг на второй полке на 2 книги больше чем на первой а на третьей полке в 4 раза меньше чем на первой и второй полках вместе сколько книг стояло на четвёртой полке если всего на четырёх полках было 32 книги?

Answer 1

1) 9 + 2 = 11 (шт) - на второй полке
2) 9 + 11 = 20
3) 20 : 4 = 5 (шт) - на третьей
4) 32 - 9 - 11 - 5 = 7 книг

Answer 2

9+2=11 книг на второй полке
(9+11):4=5 книг на третьей полке
32-(11+9+5)=7 книг на четвертой полке

Answer 3

Problem Analysis

We are given the following information: - There are 9 books on the first shelf. - There are 2 more books on the second shelf than on the first shelf. - The number of books on the third shelf is 4 times less than the combined number of books on the first and second shelves. - The total number of books on all four shelves is 32.

We need to find the number of books on the fourth shelf.

Solution

Let's solve this problem step by step.

1. Let's assume the number of books on the first shelf is x. 2. According to the given information, the number of books on the second shelf is x + 2. 3. The number of books on the third shelf is 4 times less than the combined number of books on the first and second shelves. So, the number of books on the third shelf is (x + x + 2) / 4. 4. The total number of books on all four shelves is 32. So, we can write the equation: x + (x + 2) + (x + x + 2) / 4 + x + x + 2 + (x + x + 2) / 4 = 32.

Let's solve this equation to find the value of x.

Calculation

x + (x + 2) + (x + x + 2) / 4 + x + x + 2 + (x + x + 2) / 4 = 32

Simplifying the equation: 4x + 4(x + 2) + (x + x + 2) + 4(x + x + 2) = 128 4x + 4x + 8 + 2x + 2 + 4x + 4x + 8 = 128 16x + 18 = 128 16x = 128 - 18 16x = 110 x = 110 / 16 x = 6.875

Since the number of books cannot be a fraction, we need to round down the value of x to the nearest whole number.

Therefore, the number of books on the first shelf is 6.

Now, we can find the number of books on the second shelf: x + 2 = 6 + 2 = 8

The number of books on the third shelf is: (x + x + 2) / 4 = (6 + 6 + 2) / 4 = 14 / 4 = 3.5

Again, we need to round down the value of 3.5 to the nearest whole number.

Therefore, the number of books on the third shelf is 3.

Finally, we can find the number of books on the fourth shelf: Total number of books - (number of books on the first shelf + number of books on the second shelf + number of books on the third shelf) = 32 - (6 + 8 + 3) = 32 - 17 = 15

Therefore, there are 15 books on the fourth shelf.

Answer

There are 15 books on the fourth shelf.