Question

в первый день в магазине было продано 30% картошки.во второй- 40% ОСТАВШЕГОСЯ картофеля,а в третий день-последние 84 кг.сколько всего килограммов картофеля было первоначально?ответ 200 кг-знаем.а как все расписать?

Answer 1

пусть х кг продали за три дня

тогда 0.3х кг в 1 дн.    100%-30%=70% осталось после 1 дн.

0.4*0.7 х=0.28х кг во 2дн.

100% -30%-0.28%=42% осталось на 3 дн.

0.42х в 3 день

0.42х=84

х=200 кг было всего 

 

Answer 2

пусть х будет - вся картошка.

тогда в 1-ый день продали - 0,3х

во второй  - (х - 0.3х) * 0,4

в третий - 84 кг

составляем уравнение:

0,3х + ((х - 0,3х) * 0,4) + 84 = х

0,3х+0,4х - 0,12х + 84 = х

0,3х+0,4х - 0,12х - х = -84

- 0,42х = - 84

х = - 84: (-0,42)

х = 200

Answer 3

Problem Analysis

To solve this problem, we need to determine the total weight of potatoes initially. We are given that 30% of the potatoes were sold on the first day, 40% of the remaining potatoes were sold on the second day, and the remaining weight of potatoes on the third day was 84 kg.

Solution

Let's assume the total weight of potatoes initially was x kg.

On the first day, 30% of the potatoes were sold, which means 70% of the potatoes remained. Therefore, the weight of potatoes remaining after the first day is 0.7x kg.

On the second day, 40% of the remaining potatoes were sold, which means 60% of the potatoes remained. Therefore, the weight of potatoes remaining after the second day is 0.6 * 0.7x kg.

On the third day, the remaining weight of potatoes was 84 kg. Therefore, we can set up the equation:

0.6 * 0.7x = 84

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

Calculation

Let's solve the equation to find the value of x:

0.6 * 0.7x = 84

0.42x = 84

x = 84 / 0.42

x = 200

Answer

The total weight of potatoes initially was 200 kg.

Verification

To verify the answer, let's calculate the weight of potatoes remaining after each day:

- First day: 30% sold, 70% remaining = 0.7 * 200 = 140 kg remaining - Second day: 40% of remaining sold, 60% remaining = 0.6 * 140 = 84 kg remaining

The weight of potatoes remaining after the third day is indeed 84 kg, which matches the given information. Therefore, the answer of 200 kg is correct.