Consider the following graph of a distribution for the prices for various bottles of California-produced wine.
Which of the following statements about this distribution is least accurate?
A) |
The graph could be of the sample $16, $12, $15, $12, $17, $30 (ignore graph scale). | |
B) |
The distribution is positively skewed. | |
C) |
Approximately 68% of observations fall within one standard deviation of the mean. | |
This statement is true for the normal distribution. The above distribution is positively skewed. Note: for those tempted to use Chebyshev’s inequality to determine the percentage of observations falling within one standard deviation of the mean, the formula is valid only for k > 1.
The other statements are true. When we order the six prices from least to greatest: $12, $12, $15, $16, $17, $30, we observe that the mode (most frequently occurring price) is $12, the median (middle observation) is $15.50 [(15 + 16)/2], and the mean is $17 (sum of all prices divided by number in the sample). Time-Saving Note: Just by ordering the distribution, we can see that it is positively skewed (there are large, positive outliers). By definition, mode < median < mean describes a positively skewed distribution.
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