If 2 people are digging a hole in 5 hours then how many people does it take to dig a hole in 5 minutes?

For Grade 5 Math

Guest Mar 3, 2015

#2**+10 **

I always find these questions super tricky.

I am going to do it without algebra. :)

2 people take 5hours

If you have more people, it would take less time - that makes sense doesn't it?

so

2*5people take 5 ÷ 5 hours

10 people take 1 hour

now 5 minutes is 5/60=1/12 of an hour

10*12 people would take 1/12 hours

120 people will take 5 minutes

Of course they would all get in each others way so I do not think it would really work that way. LOL

Melody
Mar 3, 2015

#1**+10 **

This is known as a "see-saw" problem.....that is, the product of one side of the equation must equal the product of the other side

So, two people dig a hole in 5 hrs. = 300 minutes

So

2 x 300 = N * 5 where N is the number of people we're looking for

600 = N * 5 divide by 5

120 = N

So it takes 120 people to dig the same hole in 5 minutes

To see the logic of this, we need to dig the hole 60 times as fast......therefore....we need 60 times as many people.... and 60 x 2 = 120.....!!!

CPhill
Mar 3, 2015

#2**+10 **

Best Answer

I always find these questions super tricky.

I am going to do it without algebra. :)

2 people take 5hours

If you have more people, it would take less time - that makes sense doesn't it?

so

2*5people take 5 ÷ 5 hours

10 people take 1 hour

now 5 minutes is 5/60=1/12 of an hour

10*12 people would take 1/12 hours

120 people will take 5 minutes

Of course they would all get in each others way so I do not think it would really work that way. LOL

Melody
Mar 3, 2015