Question

Два садовника взялись посадить 180 деревьев.Один может выполнить эту работу за 36 часов, а другой за 45 часов. За сколько часов они выполнят эту работу, работая вместе??

Answer 1

1) 180:36=5 (дер.) - сажает в час первый садовник
2) 180:45=4 (дер.) - сажает в час второй садовник
3) 5+4=9 (дер.) - посадят оба садовника за час
4) 180:9=20 (ч.)
Ответ: за 20 часов они выполнят эту работу, работая вместе.

Answer 2

Problem Analysis

Two gardeners are tasked with planting 180 trees. One gardener can complete the task in 36 hours, while the other can complete it in 45 hours. We need to determine how long it will take for them to complete the task if they work together.

Solution

To solve this problem, we can use the concept of work rates. The work rate of a person is defined as the amount of work they can complete in a unit of time. In this case, we can calculate the work rates of each gardener.

Let's assume that the work rate of the first gardener is x trees per hour. Since the first gardener can complete the task in 36 hours, we can set up the equation:

x trees/hour * 36 hours = 180 trees

Simplifying the equation, we find that the work rate of the first gardener is:

x = 180 trees / 36 hours = 5 trees/hour Similarly, let's assume that the work rate of the second gardener is y trees per hour. Since the second gardener can complete the task in 45 hours, we can set up the equation:

y trees/hour * 45 hours = 180 trees

Simplifying the equation, we find that the work rate of the second gardener is:

y = 180 trees / 45 hours = 4 trees/hour Now that we have the work rates of both gardeners, we can determine their combined work rate when they work together. The combined work rate is simply the sum of their individual work rates:

Combined work rate = x + y = 5 trees/hour + 4 trees/hour = 9 trees/hour

Finally, to find the time it will take for them to complete the task when working together, we can use the formula:

Time = Total work / Combined work rate = 180 trees / 9 trees/hour = 20 hours

Therefore, it will take the two gardeners 20 hours to complete the task when working together.

Answer

The two gardeners will complete the task of planting 180 trees in 20 hours when working together.