In: Statistics and Probability
Exam 2 scores of the class are given below
80, 52, 69, 78, 34, 67, 99, 76, 67, 56, 68, 78, 77, 79
X | (X - X̄)² | |
total sum | 980 | 3074.00 |
n | 14 | 14 |
mean = ΣX/n =
980.000 / 14 =
70.00
Variance = Σ(X - X̄)²/(n)=
3074.0000 / 14 =
219.5714
Std dev = √ [ Σ(X - X̄)²/n] =
√ (3074/14) =
14.8179
maximum = 99
minimum= 34
range=max-min = 99 -
34 = 65
mode= highest frequency data = 67, 78
Median=0.5(n+1)th value = 7.5th
= 72.500
z score = x- mean / standard deviation
= 84.8 - 70 / 14.8179 = 0.9988
=P(Z ≤ 0.9998 ) = 0.84
which tells 84% (percentile)students score below
Jake