Number of the 61 days in 2009 the Dow decreased by more than 1% is 0.514.
Given that, 61 days in 2009 the Dow decreased by more than 1%.
Normal distribution, also known as the Gaussian distribution, is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean.
In 2009
z = (1- (-0.198))/2.331
= 0.514
In 2010
z = (1-0.078)/0.821
= 1.123
Therefore, number of the 61 days in 2009 the Dow decreased by more than 1% is 0.514.
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