Answer

Verified

455.7k+ views

Hint: At first find out the value of a unit. That means how many workers will be required to do the work in one hour. Then calculate how many workers will be required to do the work in 35 hours.

It is given in the question that 7 workers can build a trench in 25 hours. First we have to find out how many workers will be required to build the same trench in one hour.

We can solve this problem using a unitary method in which we find the value of a unit and then the value of a required number of units.

Always write the things to be found on the right hand side and things known on the left hand side.

Here we have to find out how many workers we need. So, the unknown is the number of workers. We have to put this on the right hand side.

We know about the hours. So, we will take hours on our left hand side.

In 25 hours 7 workers can build a trench.

If we have to finish the same work in one hour we will need more manpower. Therefore,

In 1 hour $7\times 25$ workers can build the trench.

In 35 hours $\dfrac{7\times 25}{35}$ workers can build the trench.

So, we need $=\dfrac{7\times 25}{35}=5$ workers to build the same trench in 35 hours.

Hence, we need 5 workers to build the same trench in 35 hours.

Note: We generally make mistakes when we calculate the value of a unit. We need to understand by reading the question that the value of a unit is increasing or decreasing. If it is decreasing then we have to divide and if it is increasing then we have to multiply.

__Complete step-by-step answer:__It is given in the question that 7 workers can build a trench in 25 hours. First we have to find out how many workers will be required to build the same trench in one hour.

We can solve this problem using a unitary method in which we find the value of a unit and then the value of a required number of units.

Always write the things to be found on the right hand side and things known on the left hand side.

Here we have to find out how many workers we need. So, the unknown is the number of workers. We have to put this on the right hand side.

We know about the hours. So, we will take hours on our left hand side.

In 25 hours 7 workers can build a trench.

If we have to finish the same work in one hour we will need more manpower. Therefore,

In 1 hour $7\times 25$ workers can build the trench.

In 35 hours $\dfrac{7\times 25}{35}$ workers can build the trench.

So, we need $=\dfrac{7\times 25}{35}=5$ workers to build the same trench in 35 hours.

Hence, we need 5 workers to build the same trench in 35 hours.

Note: We generally make mistakes when we calculate the value of a unit. We need to understand by reading the question that the value of a unit is increasing or decreasing. If it is decreasing then we have to divide and if it is increasing then we have to multiply.

Recently Updated Pages

What number is 20 of 400 class 8 maths CBSE

Which one of the following numbers is completely divisible class 8 maths CBSE

What number is 78 of 50 A 32 B 35 C 36 D 39 E 41 class 8 maths CBSE

How many integers are there between 10 and 2 and how class 8 maths CBSE

The 3 is what percent of 12 class 8 maths CBSE

Find the circumference of the circle having radius class 8 maths CBSE

Trending doubts

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

Which are the Top 10 Largest Countries of the World?

Give 10 examples for herbs , shrubs , climbers , creepers

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

10 examples of law on inertia in our daily life

Write a letter to the principal requesting him to grant class 10 english CBSE

In 1946 the Interim Government was formed under a Sardar class 11 sst CBSE

Change the following sentences into negative and interrogative class 10 english CBSE