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**sweetangel786****Member**- Registered: 2006-03-18
- Posts: 20

hi, i need some help on algebra equations and how to solve them i also need help with other maths...

i have my SAT's in 6weeks and i have my math mock's on tuesday ... can u help me.

does anyone understand ratio: i don't ...

andrea and alex were making firut punch for 5 people.

they mixed together 1 litre of lemonade, 0.5 litres of orange juice and 0.25 litres of cranberry juice.

(a) write down the ratio of lemonade: orange juise : ceranberry juice, using whole numbers only.

(b) how much of each ingredient would they need to have enough punch for 8 people?

*Last edited by sweetangel786 (2006-03-18 08:05:37)*

practise makes people perfect, but nobody's perfect so why practise...

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,608

For me, I like to write down the ratios like this:

lemonade : orange : cranberry

In this case they are:

1 : 0.5 : 0.25

You are asked to make them whole numbers. So "0.5" and "0.25" are not whole numbers, and they should be. If you multiply 0.25 by 4, you will get "1", which *is* a whole number.

But with ratios, if you increase one value you should increase all values in a similar way (or else the punch will taste wrong). So, if you multiply one value by 4, then you have to multiply ALL values by 4. Like this:

1×4 : 0.5×4 : 0.25×4

Which becomes:

4 : 2 : 1

And they are all whole numbers! (Note: there was a certain amount of luck that just fixing the "0.25" by multiplying by 4 also ended up with the other two values as whole numbers)

For the second question, you already know the recipe for 5 litres (1 : 0.5 : 0.25) but need to increase everything to make 8 litres, so try multiplying all values by 8/5

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**sweetangel786****Member**- Registered: 2006-03-18
- Posts: 20

thanx, that math reli helped me... i got my math mocks on tuesday, i need help with equations i don't really understand them when you have to use algebra anf formulas.

e.g.

5y - 2 = 3y + 6 i don't understand this because my math teachr says you have to put the numbers on 1 seide and the letters on another side. i get really confused with these kind of problems.

practise makes people perfect, but nobody's perfect so why practise...

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,786

sweetangel786, your teacher is right!

the equation 5y - 2 = 3y + 6 has to be rearranged.

Bring 3y from the right hand side to the left hand side, and take -2 from the left hand side to the right hand side.

just remember, when you change the sdies of numbers or letters, you got to change their signs. That is, in this case 3y becomes -3y and -2 becomes +2.

Now the equation becomes

5y - 3y = 6 + 2

or 2y = 8

Now, it has become quite simple.

If two apples cost $8, you know each costs $4.

Similarly, if 2y = 8, y = 8/2 = 4.

Therefore, y=4 is the solution.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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**sweetangel786****Member**- Registered: 2006-03-18
- Posts: 20

thanx ganesh that has really helped me alot, i know i'll pass my mocks on tuesday... i also need help on understanding mass of units...

e.g kilograms, metres, kilomitreres when it comes to finding the distance. i also need help to understand pythagoras thereom. and some help on algebra substitutions, expanding brackets and simultaneous equations. these get me really confused when i have practise test in class these questions are on nearly most of the exam pages.

*Last edited by sweetangel786 (2006-03-19 00:23:24)*

practise makes people perfect, but nobody's perfect so why practise...

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,786

Good wishes, sweetangel786!

1 kilogram = 1000 grams

1 gram = 1000 milligrams.

Kilogram is the SI (System Internationale) Unit.

Similarly,

1 kilometre = 1000 metres

1 metre = 100 centimetres = 1000 millimetres.

Metre is the SI unit of length (and distance).

Pythagoras theorem states that the sum of squares of two sides of a right angled triangled is equal to the square of the third side(the longest side, called the hypotenuse).

a² + b² = c² |

| \

a| \c

| \

-------

b

For example, if the two sides of a right angled triangle are 3 units and 4 units, the third side is 5 units because

3² + 4² =5².

Go to this link for simultaneous equations!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

And the Pythagoras Theorem page on this website.

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