2. The standard deviation of a symmetrical distribution is 3 and the v...
Solution:
Given, standard deviation, σ = 3
Fourth moment about mean, μ = 243
To determine whether the distribution is leptokurtic or not, we need to calculate the kurtosis coefficient.
Kurtosis coefficient:
Kurtosis is a measure of the peakedness of the distribution. The kurtosis coefficient is given by:
β2 = μ4/σ^4 - 3
where β2 is the kurtosis coefficient.
Substituting the given values, we get:
β2 = (243/3^4) - 3
β2 = 9 - 3
β2 = 6
Interpretation:
Since the kurtosis coefficient is greater than 3, i.e., β2 > 3, the distribution is leptokurtic.
Leptokurtic distribution:
A leptokurtic distribution is one in which the peak of the distribution is higher and sharper than that of a normal distribution, implying that the distribution has more data points clustered around the mean. In other words, the tails of a leptokurtic distribution are fatter than those of a normal distribution.
Justification:
Hence, based on the calculated kurtosis coefficient, we can conclude that the given distribution is leptokurtic.