Question

В дремучем лесу 7/20 всех деревьев составляют колючки ели, 1/4 всех деревьев бабушки ивы, а 2/5 остатка дедушки дубы. Сколько деревьев каждого вида в лесу, если всего деревьев 1000?

Answer 1

1) 1000 * 7/20 = 350 колючки ели
2) 1000 *1/4 = 250 бабушки ивы
3)1000 -350 - 250 = 400 дедушки дубы 
или
3) 1000 *2/5 = 400 дедушки дубы 

Answer 2

Problem Analysis

We are given the information that in a dense forest, 7/20 of all trees are spruce trees, 1/4 of all trees are grandmother's ivy trees, and 2/5 of the remaining trees are grandfather's oak trees. We need to determine the number of trees of each type in the forest, given that there are a total of 1000 trees.

Solution

To solve this problem, we can follow these steps:

1. Calculate the number of spruce trees in the forest. 2. Calculate the number of grandmother's ivy trees in the forest. 3. Calculate the number of grandfather's oak trees in the forest. 4. Calculate the number of remaining trees in the forest. 5. Verify that the sum of all tree types equals the total number of trees.

Let's calculate each step in detail.

Step 1: Calculate the number of spruce trees

We are given that 7/20 of all trees are spruce trees. To calculate the number of spruce trees, we can multiply the total number of trees by the fraction 7/20.

Number of spruce trees = (7/20) * 1000

Step 2: Calculate the number of grandmother's ivy trees

We are given that 1/4 of all trees are grandmother's ivy trees. To calculate the number of grandmother's ivy trees, we can multiply the total number of trees by the fraction 1/4.

Number of grandmother's ivy trees = (1/4) * 1000

Step 3: Calculate the number of grandfather's oak trees

We are given that 2/5 of the remaining trees (after accounting for spruce and grandmother's ivy trees) are grandfather's oak trees. To calculate the number of grandfather's oak trees, we need to subtract the number of spruce trees and grandmother's ivy trees from the total number of trees, and then multiply the result by the fraction 2/5.

Number of grandfather's oak trees = (2/5) * (total number of trees - number of spruce trees - number of grandmother's ivy trees)

Step 4: Calculate the number of remaining trees

To calculate the number of remaining trees, we need to subtract the number of spruce trees, grandmother's ivy trees, and grandfather's oak trees from the total number of trees.

Number of remaining trees = total number of trees - number of spruce trees - number of grandmother's ivy trees - number of grandfather's oak trees

Step 5: Verify the sum of all tree types

To verify that our calculations are correct, we can add up the number of spruce trees, grandmother's ivy trees, grandfather's oak trees, and the number of remaining trees. The sum should equal the total number of trees.

Sum of all tree types = number of spruce trees + number of grandmother's ivy trees + number of grandfather's oak trees + number of remaining trees

Now, let's calculate the values for each step.

Calculation

Step 1: Calculate the number of spruce trees: Number of spruce trees = (7/20) * 1000 = 350

Step 2: Calculate the number of grandmother's ivy trees: Number of grandmother's ivy trees = (1/4) * 1000 = 250

Step 3: Calculate the number of grandfather's oak trees: Number of grandfather's oak trees = (2/5) * (1000 - 350 - 250) = 200

Step 4: Calculate the number of remaining trees: Number of remaining trees = 1000 - 350 - 250 - 200 = 200

Step 5: Verify the sum of all tree types: Sum of all tree types = 350 + 250 + 200 + 200 = 1000

Answer

Based on the calculations, we can conclude that in the forest, there are: - 350 spruce trees - 250 grandmother's ivy trees - 200 grandfather's oak trees - 200 remaining trees

Please note that the calculations are based on the given fractions and the assumption that the total number of trees is 1000.