Question

От мотка провода отрезали сначала 30 %, а затем еще 60 % остатка. После этого в мотке осталось 42 м провода. Сколько метров провода было в мотке первоначально?

Answer 1

пусть было х метров провода. Когда отрезали 30% в мотке осталось х-0,3х=0,7х. От остатка отрезали 60%, т.е. 0,7х*0,6=0,42х. И в мотке осталось 0,7х-0,42х=0,28х, что составило 42 метра. Чтобы найти число по его дроби нужно число разделить на эту дробь 42/0,28=150 метров.

ответ: 150 метров провода было в мотке. 

Answer 2

Calculation of the Initial Length of Wire in the Coil

To determine the initial length of wire in the coil, we can use the information provided.

According to the question, the wire was initially cut by 30% of its length, and then an additional 60% of the remaining length was cut. After these two cuts, there were 42 meters of wire remaining in the coil.

Let's calculate the initial length of the wire step by step:

1. First cut: 30% of the initial length. 2. Second cut: 60% of the remaining length after the first cut. 3. Subtract the total length of the two cuts from the remaining length to find the initial length.

Let's calculate it:

1. First cut: 30% of the initial length. - This means that 70% of the initial length remains after the first cut. - Let's represent the remaining length after the first cut as x.

2. Second cut: 60% of the remaining length after the first cut. - This means that 40% of the remaining length after the first cut is cut. - 40% of x is equal to 42 meters. - We can set up the equation: 0.4 * x = 42.

Now, let's solve the equation to find the value of x:

0.4 * x = 42

Dividing both sides of the equation by 0.4:

x = 42 / 0.4

x = 105

Therefore, the remaining length after the first cut (x) is 105 meters.

3. Subtract the total length of the two cuts from the remaining length to find the initial length: - The initial length of the wire can be calculated by adding the lengths of the two cuts to the remaining length after the second cut. - The first cut was 30% of the initial length, which is 0.3 * 105 = 31.5 meters. - The second cut was 60% of the remaining length after the first cut, which is 0.6 * 105 = 63 meters. - The initial length of the wire can be calculated as follows: 105 + 31.5 + 63 = 199.5 meters.

Therefore, the initial length of the wire in the coil was 199.5 meters.