Go to navigation
It is currently Sat Dec 03, 2016 2:29 am

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: Letts question
PostPosted: Thu Sep 04, 2014 8:58 pm 
Offline

Joined: Sat Apr 20, 2013 5:27 am
Posts: 241
30 people go to a restaurant. All the diners order from the below menu;
Three course meal: £12
Two course meal: £9

If the total bill was £345, how many people ordered a three course meal?

How do I explain the method to DD?

Could anyone please guide me?


Top
 Profile  
 
 Post subject: Re: Letts question
PostPosted: Thu Sep 04, 2014 9:09 pm 
Offline

Joined: Mon Feb 12, 2007 1:21 pm
Posts: 11931
Think about how the answer can end in a 5 in the units ...


Top
 Profile  
 
 Post subject: Re: Letts question
PostPosted: Thu Sep 04, 2014 9:24 pm 
Offline

Joined: Thu Sep 04, 2014 9:09 pm
Posts: 1
345= 12 a + 9b -----1

where a =no of peeps eating 3 course
B = no peeps eating 2 course


30 people eating therefore a+b = 30 ----------2

Simply simultaneous equations now:

A= 30 - b. subst into equation 1

345= 12(30-b) +9b
345 = 360-12b+9b

15=3b
B= 5

From ------2. 30=a+5

a= 25

Therefore 25 peeps ate a 3 course meal and 5 ate a two course meal


Top
 Profile  
 
 Post subject: Re: Letts question
PostPosted: Thu Sep 04, 2014 9:26 pm 
Offline

Joined: Wed Dec 14, 2011 9:54 am
Posts: 211
DS split 345 into multiples of 9 and 12, and by just looking at number he saw a pattern 300 and 45, and could see 45 is a multiple of 9, (9 x5) and 12 goes into 300 25 times hence, 25 people ordered £12 main course


Top
 Profile  
 
 Post subject: Re: Letts question
PostPosted: Fri Sep 05, 2014 9:56 am 
Offline

Joined: Sat Apr 20, 2013 5:27 am
Posts: 241
Thanks everyone. dd gets it now. not sure if she will be able to apply this in the exam scenario ..tomorrow.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
CALL 020 8204 5060
   
Privacy Policy | Refund Policy | Disclaimer | Copyright © 2004 – 2016