Question

Помогите пожалуйста! НЕ УРАВНЕНИЕМ! Три математика ехали в разных вагонах одного и того же поезда. Подъезжая к станции, они начали подсчитывать скамейки на привокзальном перроне. У них получилось 7, 12 и 15 скамеек. Отъезжая от станции, математики стали заново подсчитывать количество скамеек, причём один насчитал скамеек в три раза больше, чем другой. Сколько скамеек насчитал третий (математик, у которого при первом подсчёте получилось 15 скамеек)? Запишите решение и ответ.

Answer 1

Ответ:

Пошаговое объяснение:

Пусть:

математик А насчитал 15 скамеек,

математик В насчитал 12 скамеек,

математик С насчитал 7 скамеек.

Разница в скамейках:

А-С=15 - 7 = 8

А-В=15 - 12 = 3

В-С=12 - 7 = 5.

Теперь отъезжаем:

Если после отъезда со станции А 1 насчитает  1 скамейку, то В=1+3=4 и С=1+8=9 - не подходит.

Если после отъезда со станции А 1 насчитает  2 скамейки, то В=2+3=5 и С=2+8=10 - не подходит.

Если после отъезда со станции А 1 насчитает  3 скамейки, то В=3+3=6 и С=3+8=11 - не подходит.

Если после отъезда со станции А 1 насчитает  4 скамейки, то В=4+3=7 и С=4+8=12 - этот вариант нам подходит, т.к. 12/4=3 (математик С насчитал в три раза больше скамеек, чем математик А).

Ответ: математик А (третий математик) насчитал 4 скамейки.

Answer 2

Problem Analysis

Three mathematicians are traveling in different train cars of the same train. As they approach a station, they count the number of benches on the platform. They count 7, 12, and 15 benches, respectively. When they leave the station, they count the benches again. One mathematician counts three times as many benches as another mathematician. We need to determine how many benches the third mathematician counted during the first count, where they counted 15 benches.

Solution

Let's assume that the number of benches counted by the third mathematician during the first count is x.

According to the problem, one mathematician counted three times as many benches as another mathematician during the second count. Therefore, if the third mathematician counted x benches during the first count, then another mathematician counted 3x benches during the second count.

We know that the total number of benches counted during the second count is the sum of the benches counted by all three mathematicians during the first count. This can be expressed as:

x + 3x + 15 = Total number of benches during the second count

Simplifying the equation:

4x + 15 = Total number of benches during the second count

We also know that the total number of benches during the second count is the sum of the benches counted by all three mathematicians during the first count. This can be expressed as:

7 + 12 + 15 = Total number of benches during the second count

Simplifying the equation:

34 = Total number of benches during the second count

Now we can solve for x by equating the two expressions for the total number of benches during the second count:

4x + 15 = 34

Simplifying the equation:

4x = 19

Dividing both sides by 4:

x = 19/4 = 4.75

Therefore, the third mathematician counted 4.75 benches during the first count.

Answer

The third mathematician counted 4.75 benches during the first count.