According to a Department of Labor report,the city of Detroit had a 20% unemployment rate in May of 2011.Eight working-age residents were chosen at random.What was the expected number of unemployed residents,when eight working-age residents were randomly selected?
A) 1.0
B) 1.6
C) 2.0
D) 6.4

Question

Quizplus · Accepted Answer

To find the expected number of unemployed residents, we need to multiply the total number of working-age residents (which is assumed to be very large and infinite) by the unemployment rate. 
So, 20% of the working-age population is unemployed, which means that the probability of any individual being unemployed is 0.2. 
If eight working-age residents are randomly selected, we can use the binomial distribution formula to find the expected number of unemployed residents: 
Expected number of unemployed residents = (number of trials) x (probability of success) 
Expected number of unemployed residents = 8 x 0.2 = 1.6 
Therefore, the best choice is B) 1.6.

According to a Department of Labor Report,the City of Detroit