Question

5 каменщиков выложат стены дома за 70 дней. За сколько дней сделают эту же работу: 1)14 каменщиков 2)10 каменщиков 3)25 каменщиков 4)50 каменщиковПоезд проходит путь между пунктами А и В со скоростью 65 км/ч за 20 ч. За какое время поезд пройдет тот же путь,если его скорость увеличить на 15 км/ч

Answer 1

Number of Days to Complete the Wall:

To determine the number of days it would take to complete the wall with a different number of bricklayers, we can use the concept of "man-days." A man-day represents the amount of work one person can complete in one day.

Given that 5 bricklayers can complete the wall in 70 days, we can calculate the total man-days required to complete the wall as follows:

Total man-days = Number of bricklayers * Number of days

Using this formula, we can calculate the number of days required for different numbers of bricklayers:

1) 14 bricklayers: Total man-days = 14 * 70 = 980 Therefore, it would take 980 man-days to complete the wall with 14 bricklayers.

2) 10 bricklayers: Total man-days = 10 * 70 = 700 Therefore, it would take 700 man-days to complete the wall with 10 bricklayers.

3) 25 bricklayers: Total man-days = 25 * 70 = 1750 Therefore, it would take 1750 man-days to complete the wall with 25 bricklayers.

4) 50 bricklayers: Total man-days = 50 * 70 = 3500 Therefore, it would take 3500 man-days to complete the wall with 50 bricklayers.

Time to Complete the Same Distance with Increased Speed:

To calculate the time it would take for the train to travel the same distance with an increased speed, we can use the formula:

Time = Distance / Speed

Given that the train currently travels at a speed of 65 km/h and completes the distance between points A and B in 20 hours, we can calculate the distance using the formula:

Distance = Speed * Time

Using this formula, we can calculate the time required for the train to travel the same distance with an increased speed of 15 km/h:

New speed = 65 km/h + 15 km/h = 80 km/h

Time = Distance / New speed

Substituting the values:

Time = Distance / 80 km/h

To calculate the distance, we can use the formula:

Distance = Speed * Time

Substituting the values:

Distance = 65 km/h * 20 h = 1300 km

Now, we can calculate the time required for the train to travel the same distance with the increased speed:

Time = Distance / New speed = 1300 km / 80 km/h

Calculating this:

Time = 16.25 hours

Therefore, the train would take 16.25 hours to travel the same distance if its speed is increased by 15 km/h.