Answer
Since it is unusual to obtain a sample from the population of New York City in which only 11% of the people are white, the given statistics point to racial bias.
Work Step by Step
If 89% of the stops involved nonwhites, then 11% of the stops involved whites.
n = 500,000 and p = 44% = 0.44
Expected value or mean (expected number of white men/women obtained when a sample of 500,000 people are randomly selected):
$E(X)=μ_X=np=500,000\times0.44=220,000$
Standard deviation:
$σ_X=\sqrt {np(1-p)}=\sqrt {220,000\times0.44(1-0.44)}=\sqrt {220,000\times0.44\times0.56}=232.8$
$np(1-p)=220,000\times0.44\times0.56=54,208\gt10$. The probability histogram is bell shaped (see blue rectangle on page 343).
There is a probability of 95% that the number of successes (select a white man or woman when a person is randomly selected) is between $μ_X−2σ_X=220,000-2\times232.8=219,534.4$ and $μ_X+2σ_X=220,000+2\times232.8=220,465.6$. That is, there is a probability of 95% that the proportion of successes is between $\frac{219,534.4}{500,000}=0.4391=43.91$% and $\frac{220,465.6}{500,000}=0.4409=44.09$%.
It is unusual to obtain a sample from the population of New York City in which only 11% of the people are white.
