Question

Помогите решить задачу От мотка провода отрезали сначала 30%, а затем ещё 60% остатка. После этого в мотке осталось 42М провода. Сколько метров провода было в мотке первоначально?

Answer 1

42 м - это 40% от остатка, значит
42:0.4=105 м (осталось после первого отрезания)
105 м - это 70% целого провода, отсюда находим длину целого провода
105:0.7=150 м
Ответ: в мотке было 150 метров.

Answer 2

Problem Analysis

To solve this problem, we need to find the initial length of the wire based on the given information. We know that initially, 30% of the wire was cut, and then 60% of the remaining wire was cut. We also know that after these cuts, there were 42 meters of wire left in the coil.

Solution

Let's assume the initial length of the wire in the coil is L meters.

1. First cut: 30% of the wire was cut, so the remaining length of the wire is 70% of L. 2. Second cut: 60% of the remaining wire was cut, so the final length of the wire is 40% of 70% of L.

Based on the given information, we have the equation:

0.4 * 0.7 * L = 42

Now we can solve this equation to find the initial length of the wire.

Calculation

Let's solve the equation:

0.4 * 0.7 * L = 42

0.28 * L = 42

L = 42 / 0.28

L ≈ 150

Answer

The initial length of the wire in the coil was approximately 150 meters.

Please let me know if you need any further assistance!