Question

Решите задачу: За контрольную работу по математике оценки 5 и 4 получили 18 человек, что составило 75% числа всех учеников класса. Оценку 3 получили 50% остальных учеников . Сколько учеников не писали контрольную работу, если оценку 2 не получил ни один ученик?

Answer 1

Problem Analysis

To solve this problem, we need to determine the number of students who did not take the math exam. We are given that 18 students received grades of 5 or 4, which represents 75% of the total number of students in the class. Additionally, 50% of the remaining students received a grade of 3. We also know that no student received a grade of 2.

Let's break down the problem step by step to find the solution.

Solution

Step 1: Calculate the total number of students in the class.

Let's assume the total number of students in the class is x.

Step 2: Calculate the number of students who received grades of 5 or 4.

We are given that 18 students received grades of 5 or 4, which represents 75% of the total number of students in the class. We can set up the following equation:

0.75 * x = 18

Solving this equation will give us the value of x.

Step 3: Calculate the number of remaining students.

The remaining students are those who did not receive grades of 5 or 4. We can calculate this by subtracting the number of students who received grades of 5 or 4 from the total number of students:

Remaining students = x - 18

Step 4: Calculate the number of students who received a grade of 3.

We are given that 50% of the remaining students received a grade of 3. We can calculate this by multiplying the remaining students by 0.5:

Number of students who received a grade of 3 = 0.5 * (x - 18)

Step 5: Calculate the number of students who did not take the exam.

We know that no student received a grade of 2. Therefore, the number of students who did not take the exam is equal to the number of students who received a grade of 2, which is 0.

Final Answer

Based on the given information, if no student received a grade of 2, then the number of students who did not take the math exam is 0.

Please let me know if you need any further clarification or assistance!