Question

На вступительных экзаменах в университет, ученик должен ответить на 80% вопросов правильно. Петр обработал 15 вопросов. Он уверен, что на 10 из них ответил правильно. Если Петр ответит правильно на все вопросы, которые остались в тесте, он пройдет тест ровно на 80% . Сколько вопросов в тесте ?

Answer 1

18вопросов в общем получается

Answer 2

Task: Calculate the number of questions in the test

To calculate the number of questions in the test, we can use the information provided. Let's break down the information step by step:

1. The student needs to answer 80% of the questions correctly to pass the test. 2. Petr has answered 15 questions in total. 3. Petr is confident that he answered 10 of those questions correctly. 4. If Petr answers all the remaining questions correctly, he will pass the test with exactly 80%.

To find the number of questions in the test, we can set up the following equation:

(Number of questions answered correctly by Petr + Number of remaining questions) / Total number of questions = 80%

Let's solve for the number of remaining questions:

(Number of questions answered correctly by Petr + Number of remaining questions) / Total number of questions = 80%

(10 + Number of remaining questions) / Total number of questions = 80%

10 + Number of remaining questions = 0.8 * Total number of questions

Number of remaining questions = 0.8 * Total number of questions - 10

Now, we know that Petr has answered 15 questions in total. So we can substitute this information into the equation:

15 + Number of remaining questions = 0.8 * Total number of questions

Number of remaining questions = 0.8 * Total number of questions - 15

To find the total number of questions, we need to solve for it. Let's rearrange the equation:

Number of remaining questions = 0.8 * Total number of questions - 15

Number of remaining questions + 15 = 0.8 * Total number of questions

Total number of questions = (Number of remaining questions + 15) / 0.8

Now, let's substitute the given values into the equation and calculate the total number of questions:

Total number of questions = (Number of remaining questions + 15) / 0.8

Total number of questions = (0.8 * Total number of questions - 15 + 15) / 0.8

Total number of questions = Total number of questions - 15 + 15 / 0.8

Total number of questions = Total number of questions / 0.8

To find the value of Total number of questions, we need to solve the equation.