bambi_eyes
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Hey

can anyone answer this question for me (sorry in advance I don't have the answer)

Q15)

A survey was done into subjects studied at A- Level

37% of students took Mathematics

24% of students took Physics

75% of students taking Physics also took Mathematics

X is the event a student took Maths

Y is the event a student took Physics

Work out P(X U Y)


Please help!
Muchas gracias in advance
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Slowbro93
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Draw a vienn diagram and it should be clearer from there
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bambi_eyes
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(Original post by cpdavis)
Draw a vienn diagram and it should be clearer from there
But I don't know what P(X U Y ) means!
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hihihi!!!
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(Original post by bambi_eyes)
Hey

can anyone answer this question for me (sorry in advance I don't have the answer)

Q15)

A survey was done into subjects studied at A- Level

37% of students took Mathematics

24% of students took Physics

75% of students taking Physics also took Mathematics

X is the event a student took Maths

Y is the event a student took Physics

Work out P(X U Y)


Please help!
Muchas gracias in advance
37% take at least maths
24% take least physics
75% of 24% take both = 18% take both
the remainder take neither


image a venn diagram

on the circle to the left is 37% of students which take M
on the circle to the right is 6% of students which take P
in the intersection 18% of students which take P and M

p(XUY) means the probability that a student is in any of the circles or the intersection of the diagram

people inside the diagram = 37% + 6% + 18% = 61%

p(61/100)

I rushed this a bit so just check over for any mistakes, if there are any, sorry
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bambi_eyes
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(Original post by hihihi!!!)
37% take at least maths
24% take least physics
75% of 24% take both = 18% take both
the remainder take neither


image a venn diagram

on the circle to the left is 37% of students which take M
on the circle to the right is 6% of students which take P
in the intersection 18% of students which take P and M

p(XUY) means the probability that a student is in any of the circles or the intersection of the diagram

people inside the diagram = 37% + 6% + 18% = 61%

p(61/100)

I rushed this a bit so just check over for any mistakes, if there are any, sorry
Thankyou sooooooooooooo much ( rep is coming your way)

oh do you think you could explain what P( A upside down u symbol B) means as well???
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hihihi!!!
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(Original post by bambi_eyes)
Thankyou sooooooooooooo much ( rep is coming your way)

oh do you think you could explain what P( A upside down u symbol B) means as well???
that means just the middle bit between the two circles, A intersect B, your welcome
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Empty Child
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(Original post by hihihi!!!)
37% take at least maths
24% take least physics
75% of 24% take both = 18% take both
the remainder take neither


image a venn diagram

on the circle to the left is 37% of students which take M
on the circle to the right is 6% of students which take P
in the intersection 18% of students which take P and M

p(XUY) means the probability that a student is in any of the circles or the intersection of the diagram

people inside the diagram = 37% + 6% + 18% = 61%

p(61/100)

I rushed this a bit so just check over for any mistakes, if there are any, sorry
Wouldn't it just be easier to do 0.37+0.24=0.61?
Basically, U means OR
In probability, the probability of one event OR another is the probability of first event + probability of other
So probabilty of maths OR physics = 0.37+0.24
You'll just be wasting time drawing venn diagrams, i heard the time limit this year is 2 hours, which is half an hour less, learn quicker ways of doing your calculations
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hihihi!!!
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(Original post by Empty Child)
Wouldn't it just be easier to do 0.37+0.24=0.61?
Basically, U means OR
In probability, the probability of one event OR another is the probability of first event + probability of other
So probabilty of maths OR physics = 0.37+0.24
You'll just be wasting time drawing venn diagrams, i heard the time limit this year is 2 hours, which is half an hour less, learn quicker ways of doing your calculations
I explained it like that because if the question is worded differently or different values are given, its best to know how to work it out instead of taking short cuts because its an easy question? I was trying to explain how to get to the answer rather than just straight up answering the question.

Oh and my teacher said that 2:30 was a massive amount of time before, and they'll probably have less questions to accomodate the time lost. Sketching a venn diagram will waste what, 30 seconds? if it helps then I think it's time well spent
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Empty Child
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(Original post by hihihi!!!)
I explained it like that because if the question is worded differently or different values are given, its best to know how to work it out instead of taking short cuts because its an easy question? I was trying to explain how to get to the answer rather than just straight up answering the question.

Oh and my teacher said that 2:30 was a massive amount of time before, and they'll probably have less questions to accomodate the time lost. Sketching a venn diagram will waste what, 30 seconds? if it helps then I think it's time well spent
you have a good point, but if there is a harder question lurking somewhere else in the paper, then those 30 seconds are going to be precious.
And besides, you dont really need a venn diagram to answer any type of probability question (unless they ask you to draw one)
Basic rule to remember:
AND=Multiply
OR=Add
Simples.
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Katherine1
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(Original post by bambi_eyes)
Hey

can anyone answer this question for me (sorry in advance I don't have the answer)

Q15)

A survey was done into subjects studied at A- Level

37% of students took Mathematics

24% of students took Physics

75% of students taking Physics also took Mathematics

X is the event a student took Maths

Y is the event a student took Physics

Work out P(X U Y)


Please help!
Muchas gracias in advance
I did that past paper, and my teacher said that topic isn't going to come up becasue the syllabus has slightly changed... I'm not entirely sure though.
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bambi_eyes
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(Original post by Katherine1)
I did that past paper, and my teacher said that topic isn't going to come up becasue the syllabus has slightly changed... I'm not entirely sure though.
really???

could other ppl confirm this?
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Katherine1
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(Original post by bambi_eyes)
really???

could other ppl confirm this?
The stuff on conditional probability will probably come up, I mean I don't think they use those funny symbols in the new syllabus
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IAmMclovin
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(Original post by Katherine1)
I did that past paper, and my teacher said that topic isn't going to come up becasue the syllabus has slightly changed... I'm not entirely sure though.
which past paper was this question on?
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hyy
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(Original post by bambi_eyes)
really???

could other ppl confirm this?
If you are doing edexcel then conditional probability is definitely in the syllabus
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Jimesh Ullas
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#15
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#15
BY : Jimesh Ullas

37% take maths
24% physics
75% of 24% take both = (75% / 100) x 24 = 18% take both

Therefore,
= P(X) + P(Y) - P(XUY)
= 0.37 + 0.24 - 0.18
= 0.43 OR 43%
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