Expression in terms of X for the variance

AI Thread Summary
To find the variance of the set {9, 4, x, 3}, the average (x̄) is calculated as (9 + 4 + x + 3)/4. The variance formula is applied as Variance = [(9 - x̄)² + (4 - x̄)² + (x - x̄)² + (3 - x̄)²] / 4. Substituting x̄ into the variance formula leads to an expression in the form of ax² + bx + c. The discussion emphasizes the importance of using the correct statistical approach to derive the variance based on the provided numbers. Understanding the calculation of the average is crucial for accurately determining the variance.
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1. 'Find an expression in terms of x for the variance of: 9,4,x,3'
Give your answer in the form of ax^2 + bx + c

I would usually give you some information of how I could possibly tackle this question but unfortunately I have no idea. Could someone shed some light? Thanks
 
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Well, given four numbers, 9,4, BLOING,3, how would you normally calculate the variance related to this set of numbers?
 
well I'd use the statistical formula for variance
Variance = Sum of (x - xbar)^2 / n
 
So, what is the average value, xbar, with the numbers that have been given you?
 

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