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    help i am stuck i managed to work for x then i dont know what to do
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    Thats it, x is the answer.
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    it says the probability
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    Yes x is a probability. Its asking you to work out the prob that its BOTH British and from the 20th century, which is the middle probabiltiy which is x.
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    i substituted x in the expressions then i get decimal numbers
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    when check for the answer it says its wrong
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    They want the probability that, given it's British, it is also from the 20th century. The answer is the proportion of British stamps which are from the 20th century, so the solution should be X/3X = 1/3.
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    (Original post by RantingWhovian)
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    Shouldn't that first line be x(x-5) + 2x + x = 80? There are 20 stamps in the sample space but outside the given categories, right?
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    Laaaaary thank very much
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    add everything i the diagram and equate to 100. Solve for X
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    Your values for x are incorrect
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    We know that everything in the Venn diagram added together equates to 100. By subtracting 100 from both sides and collecting like terms we can form a quadratic of x^2-2x-80=0. From here we can factor into double brackets to solve for x. So (x-10)(x+8)=0. This gives us a positive value of 10 for x.
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    (Original post by Y11_Maths)
    We know that everything in the Venn diagram added together equates to 100. By subtracting 100 from both sides and collecting like terms we can form a quadratic of x^2-2x-80=0. From here we can factor into double brackets to solve for x. So (x-10)(x+8)=0. This gives us a positive value of 10 for x.
    Now it is asking us to look at the segment of British Stamps. We can substitute our value of x in to work out how many stamps are in the entire British segment
    Spoiler:
    Show
    30 stamps
    . And we know that there are only 10 stamps that are from the twentieth century in the British stamps therefore your answer would be
    Spoiler:
    Show
    10/30
    convert to a percentage
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