The accompanying table shows the average price for a gallon of gas for the 50 st

Question

The accompanying table shows the average price for a gallon of gas for the 50 states during April 2012.

Use z-scores to determine if there are any outliers in the gasoline price. (Round your answers to 2 decimal places. Negative values should be indicated by a minus sign.)

State Price per
Gallon Alaska 4.36 Alabama 3.79 Arkansas 3.76 Arizona 3.87 California 4.22 Colorado 3.89 Connecticut 4.17 Delaware 3.89 Florida 3.94 Georgia 3.83 Hawaii 4.61 Iowa 3.75 Idaho 3.77 Illinois 4.06 Indiana 3.95 Kansas 3.71 Kentucky 3.92 Louisiana 3.80 Massachusetts 3.91 Maryland 3.96 Maine 4.00 Michigan 3.93 Minnesota 3.72 Missouri 3.67 Mississippi 3.78 Montana 3.77 North Carolina 3.89 North Dakota 3.84 Nebraska 3.84 New Hampshire 3.87 New Jersey 3.80 New Mexico 3.79 Nevada 3.96 New York 4.15 Ohio 3.79 Oklahoma 3.68 Oregon 4.08 Pennsylvania 3.97 Rhode Island 3.98 South Carolina 3.72 South Dakota 3.82 Tennessee 3.77 Texas 3.81 Utah 3.71 Virginia 3.89 Vermont 3.99 Washington 4.13 Wisconsin 3.84 West Virginia 3.94 Wyoming 3.63 Boxplot of Gasoline price 4.75 - 4.50 4.25 4,0 3.75 3.50

Explanation / Answer

(a) Using the data and drawing the boxplot, it is observed that Boxplot B is the correct answer.

(b) Z-score is computed using the formula: (value - mean)/standard deviation = Z-score.
Z-score for smallest observation = - 1.48
Z-score for largest observation = 3.92
There are outliers in the data since the Z-score for the largest observation exceeded 3 by a large margin.

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