+0  
 
0
469
4
avatar

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

Best Answer 

 #2
avatar+94140 
+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
avatar+92820 
+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
avatar+94140 
+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
 #3
avatar+92820 
0

Well...that depends on how big the hole is.......maybe they're digging to China...LOL!!!

 

CPhill  Mar 3, 2015
 #4
avatar+94140 
0

well then the 120 of them had better get a wriggle on then.  :))

Melody  Mar 3, 2015

21 Online Users

avatar

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.