Question

В читальном зале библиотеки находятся 24 человека средний возраст которых 21год .Если из зала выйдет один человек, то средний возраст остальных будет равен 20 годам.Сколько лет человеку, который вышел из зала?

Answer 1

1) 24*21=504(года) - сумма лет 24 человек

2) 23 * 20 = 460(лет) - сумма лет 23 человек 

3) 504 - 460 = 44(года) - возраст человека который вышел из зала

Answer 2

1) 24*21=504(года) - сумма лет 24 человек, (1человек вышел, осталось 23чел. ) 

2) 23 * 20 = 460(лет) - сумма лет 23 человек 

3) 504 - 460 = 44(года) - возраст человека, вышедшего из зала

Answer 3

Problem Analysis

We are given that there are 24 people in the library reading room with an average age of 21 years. If one person leaves the room, the average age of the remaining people becomes 20 years. We need to determine the age of the person who left the room.

Solution

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

When there were 24 people in the room, the total age of all the people was 24 * 21 = 504 years.

When one person leaves the room, the total age of the remaining people becomes (24 - 1) * 20 = 460 years.

We can set up the following equation to solve for x:

504 - x = 460

Simplifying the equation, we get:

x = 504 - 460

x = 44

Therefore, the person who left the room is 44 years old.

Answer

The person who left the library reading room is 44 years old.