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PostPosted: Fri Jul 30, 2010 10:55 am 
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Joined: Mon Feb 16, 2009 7:52 pm
Posts: 14
Hi I am having trouble working out this type of question for my DS. Bond more fourth....here I go:-
At the local fire station they have different lenghts of hose. The shortest is half the length of the middle sized one, and one fifth of the length of the longest one. If I connect all three hoses together I make a hose of 120m long.

a) How long is the shortest hose?

b) How long is the middle hose?

c) How long is the longest hose?

I would be grateful if someone with a better mathematical brain than I could explain this :wink:


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PostPosted: Fri Jul 30, 2010 10:58 am 
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Joined: Mon Jun 18, 2007 2:32 pm
Posts: 6966
Location: East Kent
call teh shortest hose x

the middle one is twice that so =2x

longest one is 5 x so = 5x

add them together = x+2x+5x = 8x.

we know 8x = 120m so x = 120/8 = 30/2 = 15m

shortest is 15 m
next is 30m (2x15)
longest is 75m (5x15)


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PostPosted: Fri Jul 30, 2010 12:18 pm 
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Joined: Mon Feb 16, 2009 7:52 pm
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A big thankyou to you yoyo123, I am very grateful :D :D :D


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PostPosted: Fri Jul 30, 2010 5:04 pm 
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Joined: Mon Mar 15, 2010 4:52 pm
Posts: 162
If child hasn't learnt how to use algebra, they can use ratios.

Longest is 5 time shortest, middle is 2 times shortest, so ratio is 1:2:5

Total length = 120.
Share out length according to ratio.

First find the smallest unit.

120/(1+2+5) = 15

shortest = 15 ( 15*1)
middle = 30 (15*2)
longest = 75 (15*3)


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PostPosted: Fri Jul 30, 2010 7:35 pm 
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Joined: Mon Feb 16, 2009 7:52 pm
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Thankyou new2me, I shall try your way too and see which way ds can master best.


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