For this problem, note the following chart:

Age Group (in years)	% of Population in Age Group	Influenza Rate per 1,000 person-years
	CITY A	CITY B	CITY C	Massachusetts	CITY A	CITY B	CITY C
YOUNG	40%	50%	80%	60%	2	10	30
OLD	60%	50%	20%	40%	70	110	5

There are 10,000 individuals in City A, which is located in Massachusetts. Eight young individuals and 420 old individuals develop the flu over the course of a year.

• Use these data to calculate the crude influenza rate per 1,000 individuals per years in City A.
• What is the crude rate of influenza in City B?
• What is the crude rate of influenza in City C?
• Calculate an age-adjusted influenza rate for each of the cities. Use the age distribution for the State of Massachusetts (shown in the table) as the standard.