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    my exam is tomorrow
    http://qualifications.pearson.com/co...e_20120516.pdf
    can anyone do question 21? i looked at the mark scheme but it doesnt make sense
    please explain to me step by step bc i suck at maths
    thank u so much

    edit: thanks everyone xxxxxxxxxxxxx
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    Times x+2 up to the 9 and times x-2 up to the 5 so everything is on one line. So it'll be 9x+18+5x-10=5 then simplify it and solve!
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    (Original post by gameofno)
    my exam is tomorrow
    http://qualifications.pearson.com/co...e_20120516.pdf
    can anyone do question 21? i looked at the mark scheme but it doesnt make sense
    please explain to me step by step bc i suck at maths
    thank u so much
    Multiply both sides by (x+2)(x-2) and solve the quadratic that you form.
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    good luck.
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    (Original post by gameofno)
    my exam is tomorrow
    http://qualifications.pearson.com/co...e_20120516.pdf
    can anyone do question 21? i looked at the mark scheme but it doesnt make sense
    please explain to me step by step bc i suck at maths
    thank u so much
    So if you have 12 boys and the mean for one boy is 18.
    You do 12x18=216

    Then you do the same for the 8 girls with the mean of 16.5
    So you do 8x16.5=132

    Now since the question asks you for the whole group (Boys and Girls) you add the numbers together.
    132+216=348

    But since you want the mean of the whole group you have to divide by the total amount of people so.. 12 boys+8 girls= 20 students altogether.

    Then with both means added together you divide by the total number of students to get the mean of the combined group.

    132 (Mean for Girls) + 216 (Mean for Boys) / 20 (Total number of boys plus girls)= 17.4 (Mean of Boys and Girls put together)

    Hope this helps!
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    (Original post by gameofno)
    my exam is tomorrow
    http://qualifications.pearson.com/co...e_20120516.pdf
    can anyone do question 21? i looked at the mark scheme but it doesnt make sense
    please explain to me step by step bc i suck at maths
    thank u so much
    ok so first ,
    1) you have to multiply the (x+2) by the diagonally opposite number which is 92) so at the top write 9x+18
    3) then multiply the (x-2) by its diagonally opposite number which is 5
    4) which is 5x-10
    5) then ADD that onto the number at the top which is 9x+186) so at the top you now have (9x+18)+(5x-10)
    7)which simplifies down to 14x+8
    8) then at the bottom , you multiply the two bottom numbers
    9) so just write it as (x+2)(x-2)
    10) so now u have a fraction on one side and number 2 on the other side
    11) now multiplly the bottom part of ur fraction with the 2- so take the (x+2)(x-2) to the other side and multiply it by 2
    12) now you have 14x+8 = 2(x+2)(x-2)
    13) which simplfies down to 14x+8= 2x^2-8
    14) now you have to make this into a quadratic equation which equals 0
    15) so take the 8 on the left side over to the right side and make 2x^2-16
    16) then take the 14x over to the right side and make 2x^2-14x-16=0
    17)now you can see that this equation is divisible by 2 = so u can write it down as x^2-7x-8
    18) now all you have to do is factorise this to get the answer you want - im sure u know how to do thatthere will be two Xshope this helps - ik its a bit long x
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