[Emergency] Revision Techniques
#1
I'm doing revision all day today, but I've been doing some things already by creating a mind map of things, but When I went to revise Polymers (Chemistry) and Inequalities(Maths) I hit a block, I can't understand the questions and it's started not making sense, as well as I can't remember how the longer the chain of polymers changes the properties. It's just not going in anymore.
This sounds crazy but I've got exams on tuesday and it's just not going in.
This happened when I took a break for food.
I am stuck on this question in maths:
Duncan wants to buy some pencils and some ball point pens he wants to have more than twice as many pencils as ball-point pens, but must have at least 2 pens.
B. A pen costs 50p and a pencil costs 40p. Duncan has £6.50 to spread on pens and pencils. copy the inequality ()x + ()y ≤ 650 fill the blanks (marked with () ) and simplify it.

Ok after a lengthy time I came up with an answer of 5x +10y ≤ 650 but the answer sheet says 5x+ 4y=65. It makes no sense how would they simplify to that.
#2
(03-22-2015, 05:47 PM)GeneralSirens Wrote: B. A pen costs 50p and a pencil costs 40p. Duncan has £6.50 to spread on pens and pencils.

Ok after a lengthy time I came up with an answer of 5x +10y ≤ 650 but the answer sheet says 5x+ 4y=65. It makes no sense how would they simplify to that.

I think this is correct. It takes the second part of the question into consideration rather than the first bit; any better mathematicians please correct me.

I do believe it goes like this:

≤ = less than or equal to.

x = Pens

y = Pencils

() = Price

Therefore,

Price of pens + Price of pencils ≤ £6.50.


The prices for the pens and pencils are in pence, so you need to convert the total amount (£6.50) into pence also - 650.

Now, if you fill in the gaps of X + Y, you would get:
50p x X + 40p x Y ≤ 650p.

The numbers you have are 50, 40, and 650.
Now for the really difficult and intense bit. Find the highest common factor. Or the easiest. It's 10.

So now you simplify the numbers into 5, 4, and 65. (Divide 50, 40 and 650 by 10)

And there's your answer:
5x + 4y ≤ 65

I had a look at what you did.
DO NOT, I REPEAT FOR THE LOVE OF PINGU, DO NOT TRY AND SOLVE THE QUESTION.
That's where you went wrong.

-Saf
 
#3
I should probably start some proper revision...
[Image: tgRQtsH.png]
#4
Feels good to be done with school.
#5
I'm all finished now, can be closed.


Forum Jump:


Users browsing this thread: 1 Guest(s)