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# AQA D1 Linear programming constraint help watch

1. I'm stuck on writing a constraint for the following question 6a:

So far I have: (assume the crocodile symbols have a _ underneath them)
3x + 2y + z < 120
2x + y + 3z < 100
2x + 3y + z < 150

I'm stuck at finding for
'Each day, the factory must use at least twice as many components of type C as type B.'
To me this means B > 2C
however it states C > 2B for some reason which doesnt make sense since the statement says B needs at least twice as many of C or more, can anyone help me out please?
2. (Original post by Sayless)
'Each day, the factory must use at least twice as many components of type C as type B.'
To me this means B > 2C
however it states C > 2B for some reason which doesnt make sense since the statement says B needs at least twice as many of C or more, can anyone help me out please?
Rephrasing it one can say "the number of C's is going to be at least twice the number of B's", so C >= 2B

At least twice as many C as B, means there's a minimum number of the C, but no max. so the constraint is going to be along the lines of " C > ",

This type of constraint catches many people out and worth studying to ensure you understand it fully.
3. (Original post by ghostwalker)
Rephrasing it one can say "the number of C's is going to be at least twice the number of B's", so C >= 2B

At least twice as many C as B, means there's a minimum number of the C, but no max. so the constraint is going to be along the lines of " C > ",

This type of constraint catches many people out and worth studying to ensure you understand it fully.
'at least twice as many components of type C as type B'
so this statement means at least twice as many of type B make up a type C, is the key word here 'as' which helps you depict which way round the inequality goes or is it something else?
4. (Original post by Sayless)
'at least twice as many components of type C as type B'
so this statement means at least twice as many of type B make up a type C, is the key word here 'as' which helps you depict which way round the inequality goes or is it something else?
Yes, you can use the "as" as a clue.

In general it's not sufficient though.

If you had "at most twice as many components of type C as type B", it would be C <= 2B
5. (Original post by ghostwalker)
Yes, you can use the "as" as a clue.

In general it's not sufficient though.

If you had "at most twice as many components of type C as type B", it would be C <= 2B
Thanks a lot, gonna practise questions like that a lot to get better at spotting when I need to do this

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