February 27th, 2014, 08:38 PM  #1 
Senior Member Joined: Oct 2013 From: Far far away Posts: 420 Thanks: 18  women and bags
Question 1(a) Sandra can make a bag in 2 minutes. She calls 7 of her friends who also work at the same rate (a bag in 2 minute). How long will it take them to make 1200 bags? My attempt: There are 8 people. If they all start working at the same time, at the end of 2 minutes there will be 8 bags. The rate = To make 1200 bags the time required = Question 1(b) If Sandra called only 3 friends who work at the following rates: 1 bag in 3 minutes, 1 bag in 4 minutes and 1 bag in 5 minutes then, together how long will it take to make 1200 bags? My attempt: LCM (2, 3, 4, 5) = 3 x 4 x 5 = 60 minutes In 60 minutes Sandra makes 60/2 = 30 bags In 60 minutes friend 1 makes 60/3 = 20 bags In 60 minutes friend 2 makes 60/4 = 15 bags In 60 minutes friend 3 makes 60/5 = 12 bags So the rate = Therefore time taken to make 1200 bags = Is my approach to the problem correct? Is the answer correct? Is there a better way to solve this problem? Thanks 
February 27th, 2014, 08:53 PM  #2 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,475 Thanks: 886 Math Focus: Elementary mathematics and beyond  Re: women and bags 
February 27th, 2014, 09:05 PM  #3  
Senior Member Joined: Oct 2013 From: Far far away Posts: 420 Thanks: 18  Re: women and bags Quote:
 
February 27th, 2014, 09:28 PM  #4  
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 9,083 Thanks: 624  Re: women and bags Quote:
7 friends = 1 bag each in 1 minute: 7x  
February 27th, 2014, 09:37 PM  #5 
Senior Member Joined: Oct 2013 From: Far far away Posts: 420 Thanks: 18  Re: women and bags
Thanks Denis and greg1313. I made a mistake in Question 1(a). All the friends work at the same rate (1 bag in 2 minutes). SORRY for wasting your time there. What about question 1(b)? Can you have a look. 
February 27th, 2014, 11:07 PM  #6 
Global Moderator Joined: Dec 2006 Posts: 16,954 Thanks: 1256 
For 1(b), why round down? They can't quite finish 1200 bags in 935 minutes. In 936 minutes, they can finish 1201 bags (and the friend who makes a bag in each 5 minutes would have had time to work for 1 minute on the 1202nd bag).


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