As.1997
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Could someone please explain the question(s) below - I will add some more later.
Please refer to the attachment(s).

For Q2
1) Why are options B and E wrong?
2) Why is option C correct? As far as I have understood the passage, I thought it was telling us that altruism exists and the example of birds tells us that animals show some form of altruism. However, the passage claims the traditional evolutionary theory states animals are never altruistic (selfless). Therefore, does it not make sense that reciprocal altruism is "not" compatible with traditional evolutionary theory?
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nerak99
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(Original post by As.1997)
Could someone please explain the question(s) below - I will add some more later.
Please refer to the attachment(s).

For Q2
1) Why are options B and E wrong?
2) Why is option C correct? As far as I have understood the passage, I thought it was telling us that altruism exists and the example of birds tells us that animals show some form of altruism. However, the passage claims the traditional evolutionary theory states animals are never altruistic (selfless). Therefore, does it not make sense that reciprocal altruism is "not" compatible with traditional evolutionary theory?
you need to move this to the correct forum
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mqb2766
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(Original post by As.1997)
Could someone please explain the question(s) below - I will add some more later.
Please refer to the attachment(s).

For Q2
1) Why are options B and E wrong?
2) Why is option C correct? As far as I have understood the passage, I thought it was telling us that altruism exists and the example of birds tells us that animals show some form of altruism. However, the passage claims the traditional evolutionary theory states animals are never altruistic (selfless). Therefore, does it not make sense that reciprocal altruism is "not" compatible with traditional evolutionary theory?th
The second half of the paragraph fully supports C. They would only be altruistic if there was something in it for them - reciprocal.
B - unrelated to the text
E - no real mention of survival of the fittest.
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As.1997
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(Original post by mqb2766)
The second half of the paragraph fully supports C. They would only be altruistic if there was something in it for them - reciprocal.
B - unrelated to the text
E - no real mention of survival of the fittest.
For option C, doesn't the fact that the birds give warning calls and put themselves at personal risk indicate an act of selflessness i.e. altruism?
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(Original post by As.1997)
For option C, doesn't the fact that the birds give warning calls and put themselves at personal risk indicate an act of selflessness i.e. altruism?
Yes, but it's defined as reciprocal altruism in the text. They're safer overall.
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As.1997
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(Original post by mqb2766)
Yes, but it's defined as reciprocal altruism in the text. They're safer overall.
Fair enough. So I believe it is the idea that their act of altruism is not true altruism since it is carried out in the hope that they will get protection back.
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As.1997
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These are some more questions

For Q11
The answer is D. My question is what is option D even saying to us and how did they get this conclusion?
What I do understand is the table shows a higher risk for left-handed people for breast cancer in premenopausal women (2.41), which reduces postmenopause (1.12). It also shows cancer risk increases after having children (1.58).

For Q13
The answer is E which means statements 2 and 3 are correct. My question is why is option 3 correct?
According to the passage, 47% thought air travel should be limited but only 15% were willing to fly less often. Therefore, the 15% who are not willing to fly less often may not fall into the 47% who think air travel should be limited. Therefore, shouldn't option 3 be wrong???

For Q17
The answer is A. My question is what is statement 2 on about?

For Q18
The answer is 2. Not sure how you get this answer without finding the minimum droplets needed. (Note the question asks for the maximum no. of droplets needed).

For Q21
The answer is C. I got A which is wrong and I'm not sure why. Also, not sure why C is correct.

For Q22
The answer is D. Why is E wrong? Is it because E is stated in the passage already?

For Q26
The answer is D. Not sure what statement 1 is saying.
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mqb2766
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Can you do one at a time pls? Start with 11. This is a classic correlation/causal argument. You'd not expect left handedness to cause cancer, but there is a correlation. For D, the question tells you to assume the fact is true, so it says there is some hormonal change which causes both left handedness and cancer. This would cause the correlation mentioned in the question, so D is good.
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As.1997
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(Original post by mqb2766)
Can you do one at a time pls? Start with 11. This is a classic correlation/causal argument. You'd not expect left handedness to cause cancer, but there is a correlation. For D, the question tells you to assume the fact is true, so it says there is some hormonal change which causes both left handedness and cancer. This would cause the correlation mentioned in the question, so D is good.
That makes sense
(One at a time would be perfect)
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Q13) 15℅ were willing to fly less often, so 85℅ were not willing. There must be an overlap with the 47% who thought it should be limited?
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As.1997
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(Original post by mqb2766)
Q13) 15℅ were willing to fly less often, so 85℅ were not willing. There must be an overlap with the 47% who thought it should be limited?
That makes sense too.
Btw I just thought of it as a worst-case scenario -- all 15% fell in the 47% category. This still leaves 32% which say flights should be limited but are not willing to fly less.
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mqb2766
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(Original post by As.1997)
That makes sense too.
Btw I just thought of it as a worst-case scenario -- all 15% fell in the 47% category. This still leaves 32% which would said flights should be limited but are not willing to fly less.
Exactly.
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mqb2766
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Q18) you have to think about min/max volumes first, then the maximum number of droplets to give less than 1℅.
*) The volume of the water is 5 -15 cm^3. The concentration must be less than 1℅. What chemical volume should we use?
*) The volume of one droplet is 0.015-0.025 cm^3. What volume should we use to have an upper bound on the number of droplets?
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As.1997
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(Original post by mqb2766)
Q18) you have to think about min/max volumes first, then the maximum number of droplets to give less than 1℅.
*) The volume of the water is 5 -15 cm^3. The concentration must be less than 1℅. What chemical volume should we use?
*) The volume of one droplet is 0.015-0.025 cm^3. What volume should we use to have an upper bound on the number of droplets?
1) We want the max volume of water --> this is 15cm^3.
2) We want the droplet size to be the smallest possible --> 0.015cm^3
The resulting volume would be 15cm^3 of water + xcm^3 of chemical
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mqb2766
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(Original post by As.1997)
1) We want the max volume of water --> this is 15cm^3.
2) We want the droplet size to be the smallest possible --> 0.015cm^3
The resulting volume would be 15cm^3 of water + xcm^3 of chemical
The number of droplets = chemical volume / droplet volume
The question has the potential to be misleading as you want the maximum number to always ensure less than 1℅ concentration. The 1℅ concentration is the key.
You've maximised the numerator. If this was 5cm^3 of water, the concentration would be 3℅, hence invalid.
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As.1997
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(Original post by mqb2766)
The number of droplets = chemical volume / droplet volume
The question has the potential to be misleading as you want the maximum number to always ensure less than 1℅ concentration. The 1℅ concentration is the key.
You've maximised the numerator. If this was 5cm^3 of water, the concentration would be 3℅, hence invalid.
Isn't the equation supposed to be something like this:

0.015x/(15+0.015) <1/100
0.015x/(15.015) <0.01
If it was this, then x would have to be less than 2 for this equation to work -- so this must be wrong.
But I don't know where I'm going wrong with this.
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mqb2766
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(Original post by As.1997)
Isn't the equation supposed to be something like this:

0.015x/(15+0.015) <1/100
0.015x/(15.015) <0.01
You've assumed the wrong volumes. To write it like that it would be something like
n*v/(V+n*v) <= 0.01
Or
n <= V/(99v)
What volumes v,V would we use to ensure
n = V/(99v)
Has the smallest value? That is the only way to guarantee 1℅ concentration.

The maximum part comes from saying we want equality or as close to it as possible.
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As.1997
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(Original post by mqb2766)
You've assumed the wrong volumes. To write it like that it would be something like
n*v/(V+n*v) <= 0.01
Or
n <= V/(99v)
What volumes v,V would we use to ensure
n = V/(99v)
Has the smallest value? That is the only way to guarantee 1℅ concentration.

The maximum part comes from saying we want equality or as close to it as possible.
If I do 0.025x/5 <0.01
x=2 but aren't we finding the minimum number of droplets?
(I'm lost :l)
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(Original post by As.1997)
If I do 0.025x/5 <0.01
x=2 but aren't we finding the minimum number of droplets?
No, it's the maximum number of droplets that has at most 1℅ concentration. The minimum is 0 droplets. Any more than that will exceed the 1℅ concentration in some cases.

So minimum V and maximum v.
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As.1997
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I think I get what the question is asking. It is asking what is the safest maximum number of droplets that we can put to ensure we are not going above 1%. Therefore, to find this safe maximum that would be what we usually refer to the minimum number of droplets whereby we would use the upper bound for the droplet and lower bound for the water.
So that equates to:

0.025x/(5+0.025x) <0.01 (I guess we can simplify 5+0.025x to 5 because in the grand scheme it is negligible)
Therefore x=2 by trial and error.

(technically saying minimum is wrong as the minimum safest is 0)
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