Question

Инженеры использовали 50% провода, затем 80% оставшегося провода, и осталось 30 проводов. Сколько проводов было?

Answer 1

Ответ:

300 метров

Пошаговое объяснение:

50% - 0,5 части - использовали в 1- раз

1-0,5 = 0,5 части - осталось в 1-й раз

80% - это 0,8 части

0,5*0,8=0,4 части - использовали во 2-й раз

1-0,5-0,4=0,1 часть - осталось во 2-раз и это 30 метров.

Чтобы найти целое по его дроби, нужно часть целого разделить на дробь, соответвующую этой части.

30:0,1=300 метров было

Answer 2

Calculating the Number of Wires

To calculate the number of wires, we can use the information provided in the question. Let's break it down step by step.

1. Initial Usage of Wires: - Engineers used 50% of the wires.

2. Usage of Remaining Wires: - Then, they used 80% of the remaining wires.

3. Remaining Wires: - After this, 30 wires were left.

Calculation

Let's calculate the number of wires using the given information.

1. Initial Usage of Wires: - If we assume the initial number of wires as 'x', then 50% of x is used, leaving 50% of x remaining.

2. Usage of Remaining Wires: - 80% of the remaining wires were used, leaving 20% of the remaining wires.

3. Equation: - We can set up the equation based on the given information and solve for the initial number of wires, 'x'.

- 50% of x used + 80% of (50% of x) used = 30 remaining wires

Solving for x

Let's solve the equation to find the initial number of wires, 'x'.

- 0.5x + 0.8(0.5x) = 30 - 0.5x + 0.4x = 30 - 0.9x = 30 - x = 30 / 0.9 - x = 33.33 (approx)

Conclusion

The initial number of wires was approximately 33.