Flashcards
Averages + Extras
Flashcards do conjunto (10)
- 1The mode / modal group is....."The most frequent"
- 2The median is.....The middle term (when terms are ordered)
- 3The mean is.....Sum of all values / no. values
- 4The notation for the mean is given by....Σxi / n = x̄
- 5What things help us with spread?Range and IQR (usually for median)
Standard Deviation (s.d) - 6Give the 2 formulas for standard deviation:root(Σ(xi-x̄) / n)
root((Σxi^2 / n)-x̄^2) (this is expanded) - 7Give the 2 formulas for variance:Σ(xi-x̄^2)^2 / n
Σ((xi)^2 / n) - x̄^2 - 8Mean = 5 , s.d = 2 , no. terms = 50 Addition piece of data is now added. x=3 Find new s.d and mean2 = root((Σ(xi)^2 - 5^2 / 50) - 5^2)
4 = Σ(xi)^2 - 5^2 / 50) - 25
29 = Σ(xi)^2 - 5^2 / 50)
New: n=51 , Σxi = 253 , Σxi^2 = 1459
x̄=253/50 = 4.96
s.d = root(1459/51 - (253/51)^2) = 1.9996 - 9σ^2 x means....Variance
- 10σx means....S.d