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I need help with a maths problem !!

K

KurlyKatieK

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It's for my daughters homework. It's about percentages. It's about working forwards and backwards and it's DOING MY FARKING HEAD IN.

She needed to work out this:

If she has a jar of 2 different coloured buttons - there are 5875 buttons in total - and 1963 are red (the others are blue) what percentage of red buttons are in the jar.

So easy peasy. 1963 / 5875 = 0.33 X 100 = 33.4%

Yes?

BUT in working in reverse - if you 1963 x 3.34 = 6556 ?!?!?!

Shouldn't it roughly be the same?!?!?!

Kurly jnr is sleeping soundly - and I can't sleep coz this needs to make sense!!!!!!

HELP!!!
 
KurlyKatieK said:
It's for my daughters homework. It's about percentages. It's about working forwards and backwards and it's DOING MY FARKING HEAD IN.

She needed to work out this:

If she has a jar of 2 different coloured buttons - there are 5875 buttons in total - and 1963 are red (the others are blue) what percentage of red buttons are in the jar.

So easy peasy. 1963 / 5875 = 0.33 X 100 = 33.4%

Yes?

BUT in working in reverse - if you 1963 x 3.34 = 6556 ?!?!?!

Shouldn't it roughly be the same?!?!?!

Kurly jnr is sleeping soundly - and I can't sleep coz this needs to make sense!!!!!!

HELP!!!
Click to expand...
I *think* where you're going wrong is with the reverse.

You're right that 1963 is 33.4% for 5875

To go backwards: 1963/0.334 = 5877 which I assume accounts for rounding with all the extra decimal places on both ends :)
 
The easy peasy part is right.
The error in the working in the reverse part is you need to multiply the total number of buttons by the 33.4% to give 1963 red buttons. (Instead of multiplying 1963 buttons by the percentage as you have it).
i.e. 5875 x 33.4% = 1963 or 5875 x 0.334 = 1963
Hope this helps!
 
Alternatively, to find how many buttons are 100% if 1963 are 33.4%, you divide 1963 by 33.4 and then multiply by 100.
1963 ÷ 33.4 x 100 = 5877
 
I'm still confused.

But I need to sleep. IM COMING BACK TO THIS IN THE MORNING.

please help me ( and Kurly jnr lol) then!!
 
I know a lot about this topic thankfully :D

Normal: 1963 / 5875 = 0.33 X 100 = 33.4% (as you mentioned)

Reverse: For this, you multiply your decimal by the whole number.
0.33412766 (decimal obtained) x 5875 (whole number) = 1963.
 
KurlyKatieK said:
But shouldn't 1963 X 3.34 also equal 5875?
Click to expand...

No, I will explain why now.
What you do to one side, you must do to the other side.

1963 / 5875 = 0.33 <-- multiply both sides by 5875. thus cancelling out the denominator.
1963 = 0.33 x 5875 <-- divide both sides by 0.33
1963 / 0.33 = 5875. <-- make sure to use the exact decimals and not round :)

Hope this helps :)
 
JordanS said:
No, I will explain why now.
What you do to one side, you must do to the other side.

1963 / 5875 = 0.33 <-- multiply both sides by 5875. thus cancelling out the denominator.
1963 = 0.33 x 5875 <-- divide both sides by 0.33
1963 / 0.33 = 5875. <-- make sure to use the exact decimals and not round :)

Hope this helps :)
Click to expand...

Realistically though, I wouldn't go any further than the first two equations.

1963 / 5875 = 0.33 Normal
1963 = 0.33 x 5875 Reverse
 
What JordanS has provided is great. But if you're still a little confused by it, I often find a "wordy" explanation can help.
I think that algebra can often be confusing for non-math minded individuals.

It may be helpful for the OP to realise a misconception they may have with numbers. I'll try to explain in words.

The opposite of multiplying by a number by 0.334 is NOT equal to multpilying a number by 3.34.

Think about this: Is the opposite of multiplying a number by 0.5 (ie halving it) the same as multiplying it by 5.0? No. The opposite of multiplying by 0.5 (halving) is multiplying by 2 (doubling).

If you want to reverse a process, you cannot change the numbers. You can only change the operation.
ie. To reverse the process of MULTIPLYING by 0.334 you have to DIVIDE by 0.334.
The number stayed the same and only the operation was changed.

I hope this added explanation is helpful.
 
Hiya, Kismet's daughter here (Miss D), I wanna help from a student perspective.

So, assuming she would have to show every step, first it would be something along the lines of:
1963/5875 = 0.334.
0.33 x 100 = 33.4%.

When you work backward, you simply put the decimal back in as the multiplier, ie;
1963/0.334 = 5877.

The only reason that the number isn't exactly the same as the original divisor (5875) is that you've rounded to 0.334, as the full decimal is 0.3341276595744680851063829787234. But frankly, no one wants to write that all down. As long as your daughter simply states that she got the answer 5877 by rounding, I'm sure it should be fine. :thumbsup:
 
No, but I am mathematically challenged -except with respect to money. I love how you folks explained the problems. :)
 
Mrs Butterface said:
I *think* where you're going wrong is with the reverse.

You're right that 1963 is 33.4% for 5875

To go backwards: 1963/0.334 = 5877 which I assume accounts for rounding with all the extra decimal places on both ends :)
Click to expand...



(( SING IT LIKE YOKO ))




"Imagine there's no Prisus
It's easy cos she's a lie.
No Ryan or Travi below us
Above us only SKYE !
Imagine all the Pristians
at eviction, waving her bi

Imagine Prisus wasn't cunty
I know, its hard to do
Nothing to gossip or cry for
And no fake religion too
Imagine all the Pristians
Living lies in exile

You may say I'm a creamer
But I'm not a wannabe Bhushan
I hope someday you'll join us
And accept that SKYE finished #1"[DOUBLEPOST=1416582180][/DOUBLEPOST]
penelopepitstop said:
yes yes
Click to expand...



(( SING IT LIKE YOKO ))




"Imagine there's no Prisus
It's easy cos she's a lie.
No Ryan or Travi below us
Above us only SKYE !
Imagine all the Pristians
at eviction, waving her bi

Imagine Prisus wasn't cunty
I know, its hard to do
Nothing to gossip or cry for
And no fake religion too
Imagine all the Pristians
Living lies in exile

You may say I'm a creamer
But I'm not a wannabe Bhushan
I hope someday you'll join us
And accept that SKYE finished #1"
 
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