Question

A city mayor in Michigan is planning the number of new snow plows he must purchase to remove the snow next winter. The average snowfall in the past 10 years has been normally distributed with a mean of 112 inches and a standard deviation of 14 inches. What amount, in inches, separates the lowest 20% of the means of yearly snowfall in the past 10 years from the highest 80%? Use the z-table below:

z	0.00	0.01	0.02	0.03	0.04	0.05	0.06	0.07	0.08	0.09
-0.8	0.212	0.209	0.206	0.203	0.201	0.198	0.195	0.192	0.189	0.187
-0.7	0.242	0.239	0.236	0.233	0.230	0.227	0.224	0.221	0.218	0.215
-0.6	0.274	0.271	0.268	0.264	0.261	0.258	0.255	0.251	0.248	0.245
-0.5	0.309	0.305	0.302	0.298	0.295	0.291	0.288	0.284	0.281	0.278
-0.4	0.345	0.341	0.337	0.334	0.330	0.326	0.323	0.319	0.316	0.312
-0.3	0.382	0.378	0.374	0.371	0.367	0.363	0.359	0.356	0.352	0.348

Round the z-score to two decimal places. Round x¯ to the nearest whole number.

z​ -score =

x​  = inches

Answer 1