If 12 men can dig 35 holes in 14 days, how many needed to...

Simple patterns, variables, the order of operations, simplification, evaluation, linear equations and graphs, etc.
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little_dragon
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If 12 men can dig 35 holes in 14 days, how many needed to...

Postby little_dragon » Tue Dec 30, 2008 1:59 pm

If 12 men can dig 35 holes in 14 days, (a) how many men are needed to dig 35 holes in 8 days? (b) How many days would it take 12 men to dig 30 holes?

Twelve men working 14 days is (12)(14) = 168 man-days.

a: If you have 8 days and need 168 man-days, then you need (168)/(8) = 21 men.

b: Thirty-five holes in 168 man-days is (168)/(35) = 4.8 man-days per hole, so 30 holes is (4.8)(30) = 144 man-days. Then you need (144)/(12) = 12 days to dig the holes.

Is that right? Thanks! :wave:

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stapel_eliz
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Postby stapel_eliz » Tue Dec 30, 2008 7:25 pm

little_dragon wrote:Is that right? Thanks!

I've seen other methods of doing this sort of exercise, but your way (converting to man-hours, machine-days, etc) always seemed so much simpler that I never bothered trying to figure out the others. :wink:

Your work and values looks good to me! :D

Eliz.

simba
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Re: If 12 men can dig 35 holes in 14 days, how many needed to...

Postby simba » Mon Jan 12, 2009 9:50 pm

little_dragon wrote:If 12 men can dig 35 holes in 14 days, (a) how many men are needed to dig 35 holes in 8 days? (b) How many days would it take 12 men to dig 30 holes?

:confused: Where did you learn that?? :confused: that is one of those brain teasers :lol:

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little_dragon
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Re: If 12 men can dig 35 holes in 14 days, how many needed to...

Postby little_dragon » Mon Jan 12, 2009 11:38 pm

simba wrote: :confused: Where did you learn that?? :confused: that is one of those brain teasers :lol:

I'm homeschooled and I'm taking Singapore Math. :wave:

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Re: If 12 men can dig 35 holes in 14 days, how many needed to...

Postby simba » Tue Jan 20, 2009 2:57 pm

little_dragon wrote:I'm homeschooled and I'm taking Singapore Math.

:shock: :wave: so am i. so what grade are you in :?: i need help with my word problems :mrgreen:

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stapel_eliz
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Postby stapel_eliz » Tue Jan 20, 2009 5:13 pm

simba wrote:i need help with my word problems

Please post your questions as new threads. Go to the front page of the forums, pick the appropriate category or "forum", click on the name (such as "Pre-Algebra") to open the listing for that forum, and then click on the "New Topic" button (above the topic listing, on the left-hand side of the page).

Remember to include a clear listing of your work and reasoning so far. Thank you! :D

Eliz.

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Re:

Postby simba » Wed Jan 21, 2009 1:17 pm

stapel_eliz wrote:
simba wrote:i need help with my word problems

Please post your questions as new threads. Go to the front page of the forums, pick the appropriate category or "forum", click on the name (such as "Pre-Algebra") to open the listing for that forum, and then click on the "New Topic" button (above the topic listing, on the left-hand side of the page).

Remember to include a clear listing of your work and reasoning so far. Thank you! :D

Eliz.


thx :D


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