Answered By Leonardo F

In order to answer this question, we need a normal distribution table or any computational tool such as Microsoft Excel. The question is asking for the probability for the reduced variable, z, to be less than -0.23. Is we use a normal distribution table, we can look up the value of the area under the curve for which the z is -0.23. This value is approximately 0.4090. So:

P(z<-0.23) = 0.4090