Question

В бак набрали воды для полива. В первый день израсходовали 30% набранной воды, во второй — 40% оставшейся в баке воды, а в третий день — половину воды, оставшейся после первых двух дней. Какое из приведенных в ответах значений рав- но с точностью до 10 литров количеству литров воды, набранной в бак, если после трёх дней полива осталось 4 десятилитровых ведра воды?\

Answer 1

Решение:
Обозначим количество воды в баке за (х)л, тогда после первого дня воды в баке осталось:
х-30%*х:100%=х-0,3*х=х-0,3х=0,7х
После второго дня осталось воды в баке:
0,7х-40%*0,7х:100%=0,7х-0,4*0,7х=0,7х-0,28х=0,42х
Так как в третий день израсходовано половина оставшейся воды, то есть 0,42х:2=0,21х, то остаток воды после третьего дня составил:
0,42х-0,21х=0,21х , равное 4 десятилитровых ведра воды, или 40 литрам,
Отсюда:
0,21х=40
х=40:0,21
х≈190 (л)

Ответ: Бак вмещает около 190 литров воды

Answer 2

Problem Analysis

We are given the following information: - On the first day, 30% of the water in the tank was used for watering. - On the second day, 40% of the remaining water in the tank was used for watering. - On the third day, half of the remaining water after the first two days was used for watering. - After three days of watering, there were 4 ten-liter buckets of water left.

We need to determine the amount of water that was initially in the tank.

Solution

Let's assume that the initial amount of water in the tank is x liters.

On the first day, 30% of x liters of water was used, leaving 70% of x liters of water in the tank.

On the second day, 40% of the remaining 70% of x liters of water was used, leaving 60% of 70% of x liters of water in the tank.

On the third day, half of the remaining water after the first two days was used, leaving 50% of 60% of 70% of x liters of water in the tank.

According to the given information, 4 ten-liter buckets of water were left after three days of watering. Therefore, we can write the following equation:

50% * 60% * 70% * x = 4 * 10 liters

To find the value of x, we can solve this equation.

Calculation

Let's calculate the value of x using the equation mentioned above.

50% * 60% * 70% * x = 4 * 10 liters

0.5 * 0.6 * 0.7 * x = 40 liters

0.21 * x = 40 liters

x = 40 liters / 0.21

x ≈ 190.476 liters

Therefore, the initial amount of water in the tank was approximately 190.476 liters.

Answer

The initial amount of water in the tank, with an accuracy of up to 10 liters, was approximately 190.476 liters.