Question

В читальном зале библиотеки 24 человека ,средний возраст которых равен 21 году.Когда из зала вышел один человек , средний возраст остаашихся стао равным 20 годам .Сколько лет человеку,вышедшему из зала? Ответ:44года Как это все записать?

Answer 1

24×21=504. 23×20=460
504-460=44

Answer 2

Problem Statement

В читальном зале библиотеки находится 24 человека, средний возраст которых равен 21 году. Когда из зала вышел один человек, средний возраст оставшихся стал равным 20 годам. Сколько лет человеку, вышедшему из зала?

Solution

Let's solve this problem step by step.

1. We know that the average age of the 24 people in the library is 21 years. 2. When one person leaves the library, the average age of the remaining people becomes 20 years.

To find the age of the person who left the library, we can use the concept of the average.

Let's assume the age of the person who left the library is x years.

When the person leaves, the sum of the ages of the remaining people is (24 - 1) * 20, because there are 24 people initially and one person leaves.

The sum of the ages of the remaining people is also equal to the sum of the ages of all the people initially minus the age of the person who left.

So, we can write the equation as:

(24 - 1) * 20 = (24 * 21) - x

Simplifying the equation:

23 * 20 = 24 * 21 - x

Now, let's solve for x.

23 * 20 = 24 * 21 - x 460 = 504 - x x = 504 - 460 x = 44

Therefore, the age of the person who left the library is 44 years.

Answer: The person who left the library is 44 years old.