Question

Помогите пожалуйста! Два насоса, работая одновременно, могут откачать нефть из цистерны за 20 мин. Если бы первый насос работал один, то на откачку нефти ему потребовалось бы 30 мин. Сколько времени потребуется для откачки нефти второму насосу?

Answer 1

1:20=1/20 часть откачивают вместе за 1 мин
1:30=1/30 часть откачивает первый за 1 мин
1/20-1/30=1/60 часть откачивает второй за 1 мин
1:1/60=60 мин=1 час нужно второму насосу

Answer 2

Problem Analysis

We are given that two pumps can pump oil out of a tank in 20 minutes when they work together. If the first pump works alone, it takes 30 minutes to pump the oil. We need to determine how long it will take for the second pump to pump the oil alone.

Solution

Let's assume that the second pump can pump the oil alone in x minutes.

According to the given information, when both pumps work together, they can pump the oil in 20 minutes. This means that in 1 minute, they can pump 1/20th of the oil. Similarly, when the first pump works alone, it takes 30 minutes to pump the oil. So, in 1 minute, the first pump can pump 1/30th of the oil.

Now, let's calculate the rate at which the second pump can pump the oil alone. Since the first pump can pump 1/30th of the oil in 1 minute, the remaining amount of oil that needs to be pumped in 1 minute is 1 - 1/30 = 29/30. Therefore, the second pump can pump 29/30th of the oil in 1 minute.

Since we assumed that the second pump can pump the oil alone in x minutes, we can set up the following equation:

(29/30) * x = 1

Solving this equation will give us the value of x, which represents the time it takes for the second pump to pump the oil alone.

Calculation

Let's solve the equation:

(29/30) * x = 1

Multiplying both sides of the equation by 30/29:

x = 30/29

Therefore, the second pump will take approximately 1.0345 minutes to pump the oil alone.

Answer

The second pump will take approximately 1.0345 minutes to pump the oil alone.

Please let me know if I can help you with anything else.