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# Edexcel IGCSE Mathematics A - Paper 3H - 2016 - Unofficial Mark Scheme

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1. Question 21 was definitely 25/84 not 1/4 like you said. You should change it so that it's correct.
2. (Original post by Jona12334)
Question 17 was 7.5 not 8
Actually, the answer was 8. You can use the quadratic formula to get -7.5 or 8, but you can't have a negative length. Therefore, only 8 is accepted.
3. (Original post by Benjbob123)
Question 21 was definitely 25/84 not 1/4 like you said. You should change it so that it's correct.
Cheers mate, it's been corrected now.
4. Does anyone have the mark scheme for paper 3HR?!?!?!
5. (Original post by Igcse1student)
Anyone do 3HR?

Posted from TSR Mobile
That's what I'm looking for u found anything
6. How do you know the answer to Q21 is 25/84? I got 2/7
7. Question22 I got 138.8
8. Hi, Can you maybe tell us how you got 1637 for the spheres question?
Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Therefore only 1439 spheres can be made from the cube. I know I might be wrong but I cannot find any way of getting 1637 spheres. Could you please post how you got your answer?
9. (Original post by mrmaths12345)
last question was 188
probability one was 0.298
angles one was 63
cube and sphere one was 1637
all definitely correct
Hi, Can you maybe tell us how you got 1637 for the spheres question?
Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Answer: (4.55x4.55x4.55)/(4/3xπx0.25^3)= 1439.21 Therefore only 1439 spheres can be made from the cube. I know I might be wrong but I cannot find any way of getting 1637 spheres.
10. Hi,
Can you maybe tell us how you got 1637 for the spheres question? Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Therefore only 1439 spheres can be made from the cube.
I know I might be wrong but I cannot find any way of getting 1637 spheres. Could you please post how you got your answer?
11. (Original post by Niallano)
How do you know the answer to Q21 is 25/84? I got 2/7
This is the working:
The only ways to pick out three of the cards and get a total of 6 were to pick out a 1, 2 and 3; or to pick out 2,2 and 2.
The former can be achieved by picking them out in 1 of six orders:
1,2,3
1,3,2
2,3,1
2,1,3
3,1,2
3,2,1
To find out the probability of each of these scenarios, this is how you do it:
(2/9)*(3/8)*(4/7) = 1/21
Since there are 6 of them, multiply 1/21 by 6 = 2/7 (which is what you did)
However you forgot that by picking out three 2's, a total of six could be achieved.
The probability of this is (3/9)*(2/8)*(1/7)=1/84
1/84 + 2/7 = 25/84
12. (Original post by mrmaths12345)
last question was 188
probability one was 0.298
angles one was 63
cube and sphere one was 1637
all definitely correct
Hi, Can you maybe tell us how you got 1637 for the spheres question? Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube. Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere) UB of length of the cube: 4.55cm LB of the radius of the sphere: 0.25cm (note I converted to cm here) Answer: (4.55x4.55x4.55)/(4/3xπx0.25^3)= 1439.21 Therefore only 1439 spheres can be made from the cube. I know I might be wrong but I cannot find any way of getting 1637 spheres. Could you please post how you got your answer?
13. Guys, if I made the cumulative frequency graph like bar chart, what will I get for the graph itself and the interquartile range question?
14. (Original post by Martins1)
This is the working:
The only ways to pick out three of the cards and get a total of 6 were to pick out a 1, 2 and 3; or to pick out 2,2 and 2.
The former can be achieved by picking them out in 1 of six orders:
1,2,3
1,3,2
2,3,1
2,1,3
3,1,2
3,2,1
To find out the probability of each of these scenarios, this is how you do it:
(2/9)*(3/8)*(4/7) = 1/21
Since there are 6 of them, multiply 1/21 by 6 = 2/7 (which is what you did)
However you forgot that by picking out three 2's, a total of six could be achieved.
The probability of this is (3/9)*(2/8)*(1/7)=1/84
1/84 + 2/7 = 25/84
hi can i ask you what did you get for the q where you had to find the angle between the AH Line and the plane efgh ? was it 24.1 ?
15. (Original post by mrmaths12345)
last question was 188
probability one was 0.298
angles one was 63
cube and sphere one was 1637
all definitely correct

Hi, Can you maybe tell us how you got 1637 for the spheres question?
Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Answer: (4.55x4.55x4.55)/(4/3xπx0.25^3)= 1439.21 Therefore only 1439 spheres can be made from the cube. I know I might be wrong but I cannot find any way of getting 1637 spheres.
16. (Original post by Tapochek)
Guys, if I made the cumulative frequency graph like bar chart, what will I get for the graph itself and the interquartile range question?
the interquartille was 20
17. (Original post by jonitoni2)
Hi, Can you maybe tell us how you got 1637 for the spheres question?
Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Answer: (4.55x4.55x4.55)/(4/3xπx0.25^3)= 1439.21 Therefore only 1439 spheres can be made from the cube. I know I might be wrong but I cannot find any way of getting 1637 spheres.
hi can i ask you what did you get for the q where you had to find the angle between the AH Line and the plane efgh ? was it 24.1 ?
18. I have done it the same way and got the same answer, but I think that the upper bound for cube side length was 4.75 instead of 4.55, that's where the answer comes from.
19. (Original post by jonitoni2)
Hi,
Can you maybe tell us how you got 1637 for the spheres question? Wasn't the question: The cube has a side length of 4.5cm correct to the nearest 0.5cm and the sphere has a radius of 3mm correct to the nearest mm. Calculate the maximum number of spheres that can be made from the cube.
Therefore the answer would be: (Upper bound for the volume of the cube)/(Lower bound of the volume of the sphere)
UB of length of the cube: 4.55cm
LB of the radius of the sphere: 0.25cm (note I converted to cm here)
Therefore only 1439 spheres can be made from the cube.
I know I might be wrong but I cannot find any way of getting 1637 spheres. Could you please post how you got your answer?
It said that 4.5 cm was to the nearest 0.5, not 0.1. Therefore the upper bound was 4.75 not 4.55. I did the same. That is only minus two or three marks, dont worry.
20. (Original post by WhiteX)
hi can i ask you what did you get for the q where you had to find the angle between the AH Line and the plane efgh ? was it 24.1 ?
Rings a bell, but i cant really remember. If someone gives me the question I can solve it again.

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