Question

РЕБЯТА, помогите пожалуйста! Очень срочно , пожалуйста с полным решением.( дано, решение, как в чистовик)В коробке лежат зеленые и синие шары. Сколько в коробке синих шаров, если зеленых в ней 18, а вероятность того, что выбранный наугад шар окажеться синим, равна 2 ? 5

Answer 1

Пусть x-количество синих шаров, тогда (18+x) - количество всех шаров.
Составим уравнение:
x/(18+x)=2/5
5x=36+2x
3x=36|:3
x=12
Ответ:12
Удачи в решении задач!

Answer 2

Problem Analysis

We are given a box containing green and blue balls. The number of green balls in the box is 18. We need to determine the number of blue balls in the box, given that the probability of randomly selecting a blue ball is 2/5.

Solution

Let's assume the number of blue balls in the box is x.

The total number of balls in the box is the sum of the number of green balls and the number of blue balls: Total number of balls = Number of green balls + Number of blue balls

We are given that the number of green balls is 18. Therefore, we can write the equation as: Total number of balls = 18 + Number of blue balls

The probability of selecting a blue ball is given as 2/5. This means that the number of blue balls divided by the total number of balls is equal to 2/5: Number of blue balls / Total number of balls = 2/5

Substituting the expression for the total number of balls, we have: Number of blue balls / (18 + Number of blue balls) = 2/5

To solve this equation, we can cross-multiply and solve for the number of blue balls.

Calculation

Let's solve the equation to find the number of blue balls:

Number of blue balls / (18 + Number of blue balls) = 2/5

Cross-multiplying, we get: 5 * Number of blue balls = 2 * (18 + Number of blue balls)

Expanding the equation, we have: 5 * Number of blue balls = 36 + 2 * Number of blue balls

Simplifying the equation, we get: 5 * Number of blue balls - 2 * Number of blue balls = 36

Combining like terms, we have: 3 * Number of blue balls = 36

Dividing both sides of the equation by 3, we get: Number of blue balls = 36 / 3

Simplifying, we find: Number of blue balls = 12

Answer

Therefore, there are 12 blue balls in the box.