Answer
a)$−1,268,950.
b)-0.16.
c)-0.16
d)Usual.
Work Step by Step
a) Difference between Obama's net worth and the mean of the Executive Branch's members' average net worth: $\$3,670,505-\$ 4,939,455=\$-1,268,950.$
b)$z=\frac{x-\mu}{\sigma}=\frac{\$3,670,505-\$ 4,939,455}{\$7,775,948}=-0.16.$
Hence Obama's net worth is 0.16 standard deviations from the mean of the Executive Branch's members' average net worth.
c)$z=\frac{x-\mu}{\sigma}=\frac{\$3,670,505-\$ 4,939,455}{\$7,775,948}=-0.16.$
d) Obama's z-score is between -2 and 2, hence it is usual.
