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# MATHS 1-9 What have i done wrong? watch

1. The markscheme says the answer is 252 but i cant seem to understand how

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2. (Original post by z_o_e)
The markscheme says the answer is 252 but i cant seem to understand how

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Trapezium area.

3. The radius you have used is wrong. Have a look at the semi-circle again and figure out what the radius is !!!
4. (Original post by RDKGames)
Trapezium area.
I still dont see anything wrong.

A+b = 40
Divide by 2 which is 20

Times it by height which gives 280 as a total area?

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5. For the trapezium you are fine

Think about the circles. if you are removing 2 semicircles with equal diameter it is equivalent to removing one whole circle of diameter 6.

To get the area of a circle you use (pi r^2) , I think that is where you want wrong.
6. The radius is half the diameter, you used the diameter instead of the radius. When calculating the area of the semicircles.
8. (Original post by z_o_e)
I still dont see anything wrong.

A+b = 40
Divide by 2 which is 20

Times it by height which gives 280 as a total area?

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Oh didn't bother verifying the calculation. You shouldn't write something like that anyway because it is an incorrect statement and can be confusing to read for the examiner. But yes, 280 is the total area of the trapezium, now check your semicircle area.
9. (Original post by OGGUS)
The radius is half the diameter, you used the diameter instead of the radius. When calculating the area of the semicircles.
Oh shhhhhh

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10. (Original post by RDKGames)
Oh didn't bother verifying the calculation. You shouldn't write something like that anyway because it is an incorrect statement and can be confusing to read for the examiner. But yes, 280 is the total area of the trapezium, now check your semicircle area.
Thank you so much everyone

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11. Can someone help on this please

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12. (Original post by z_o_e)
Can someone help on this please

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Convert into first.
13. (Original post by RDKGames)
Convert into first.
I got 15 meters...

And then 15*28=420

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14. (Original post by z_o_e)
I got 15 meters...

And then 15*28=420

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Area get divided through by in 2 dimensions - because the length gets divided by 100 and then the width gets divided by 100 in order to turn those measurements from cm to m individually, thus you dividing the area by 100 twice, or
15. (Original post by z_o_e)
I got 15 meters...

And then 15*28=420

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F = P * A

where A = 1, 500 cm^2 = 1, 500 / (100*100) = 0.15 m^2

F = 28 M/m^2 * 0.15 m^2 = 4.2N
16. (Original post by CraigFowler)
F = P * A

where A = 1, 500 cm^2 = 1, 500 / (100*100) = 0.15 m^2

F = 28 M/m^2 * 0.15 m^2 = 4.2N
Thank you so much

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18. Ok, there are 120 counters.

3x more red counters so.. 90 red, 30 blue

carl takes 1/3 of the red counters so 60 red left.

then kerry takes 80% of blue counters away so 30/5=6 6*4=24 Then you do 30-24=6

then you need to work out the ratio:

60:6 then 10:1
19. (Original post by stoyfan)
Ok, there are 120 counters.

3x more red counters so.. 90 red, 30 blue

carl takes 1/3 of the red counters so 60 red left.

then kerry takes 80% of blue counters away so 30/5=6 6*4=24

then you need to work out the ratio:

60:24 then 20:8 then 5:2
How do you work out how kerry 80% bit?

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20. (Original post by z_o_e)
How do you work out how kerry 80% bit?

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Sorry, I made a mistake. I can see why you are highlighting stuff but don't just highlight the numbers, also highlight helpful verbs and nouns like "take" and "blue counter" or "red counter".

For example what happened was that I was only drawn to the words that you highlighted, like 80% but I didn't I didn't look at the word "taken". Therefore I didn't take 24 for 30.

I think that you can prevent these mistakes from better highlighting. .

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