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Mathematics Question Thread

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Maroon and Gold Never Fold:
Is anyone able to look over this answer as I am not sure if I have proved it properly or used correct notation. It is the second question of the phtoto (5.ii)

Thanks

fun_jirachi:
Seems about right :) - just be careful with the first line, you haven't subscripted the i, it looks like it's being multiplied onto the numerator as opposed to indexing the score

Maroon and Gold Never Fold:

--- Quote from: fun_jirachi on June 06, 2021, 08:52:03 pm ---Seems about right :) - just be careful with the first line, you haven't subscripted the i, it looks like it's being multiplied onto the numerator as opposed to indexing the score

--- End quote ---

What do you mean by I haven't subscripted the 'i'. In my picture it is being multiplied on my numerator, is that wrong?

fun_jirachi:
Yes - \(\sum_{i=1}^{n} \frac{(a+x)i}{n} = \frac{(a+x)(n - 1)}{2}\), which will lead you to an incorrect conclusion. If you notice in the formula that is given for the mean, i is a subscript denoting index (ie. \(x_i\) denotes the \(i^{\text{th}}\) score). Your first line should be something like \(\sum_{i=1}^{n} \frac{(a+x_i)}{n}\).

Maroon and Gold Never Fold:

--- Quote from: fun_jirachi on June 07, 2021, 06:24:52 pm ---Yes - \(\sum_{i=1}^{n} \frac{(a+x)i}{n} = \frac{(a+x)(n - 1)}{2}\), which will lead you to an incorrect conclusion. If you notice in the formula that is given for the mean, i is a subscript denoting index (ie. \(x_i\) denotes the \(i^{\text{th}}\) score). Your first line should be something like \(\sum_{i=1}^{n} \frac{(a+x_i)}{n}\).

--- End quote ---

thanks, should I leave the subscript 'i' on 'a' in my second line of working out then.

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