Question 420:

Asked on September 28, 2008

Tags: Z-Score

1

Answer:

No answer provided yet.

We want the z-score associated with 45% of the area under the curve (one-sided) and can look that up using the percentile to z-score calculator. You should get a z-score of -0.126.  Recall that a z-score is equal to some data-point minus the mean with that result divided by the standard deviation.Now we setup an equation and solve for the unknown value.

1. (x-1050)/218 = -0.126
2. x-1050 = -27.47
3. x = 1022.53

So the energy level of 1022.53 kWh is at the 45th percentile for this distribution. Energy above this level would be in the top 55%.