Rates

Rates are frequently used in news stories: the property tax rate, the violent crime rate, the death rate from AIDS, infant mortality and murder rates.

Rates usually are better indicators than raw numbers. For example, in a recent year, the New York metropolitan area had 803 murders, Washington, D.C., 301 murders. Although the nation's capital had less than half the number of New York's murders, its murder rate of 56.9 was almost six times New York's murder rate of 9.6.

Why? Because the rate indicates a relationship between two numbers: so many miles per hour, so much interest on a savings account balance, so much tax on every $1,000 of property valuation. In the case of murders, the relationship is between the number of murders and the population of the area in which the murders occurred.

New York: Population, 8.6 million; number of murders, 803.
Washington: Population, 529,000; number of murders, 301.

A rate is the result of dividing one number by the other number in the relationship. In the case of crime, the top number is the number of crimes; the bottom number is the population. For murder:

New York Metropolitan Area
803 / 8,600,000,000 = .0000933

Washington, D.C.
301 / 529,000 = .0005689

To get rid of the awkward decimal, we make the rate the number of murders per 100,000 population, which allows us to move the decimal five places to the right:

New York Metropolitan Area: 9.33, rounded to 9.3.
Washington, D.C.: 56.89, rounded to 56.9.

<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0073511935/567267/Part6_Rates1.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (31.0K)</a> Jack L. Kirkland, The Knoxville News-Sentinel

1			There were 1,635,000 violent crimes in the United States in a recent year when the population was 274 million. The violent crime rate per 100,000 residents was
			A)	163.9
			B)	596.7
			C)	436.8
			D)	Do not know.
2			In the Minneapolis-St. Paul metropolitan area there were 12,650 violent crimes in a recent year. The population in the area is 2.8 million. The violent crime rate was
			A)	221.3
			B)	126.5
			C)	451.8
			D)	Do not know.
3			There are 161, 000 dentists in the United States. What is the rate per 100,000 population? (See U.S. population in question No. 1)
			A)	166
			B)	58
			C)	100
			D)	Do not know
4			Nevada has 590 dentists and ranks 41st in the country in number of dentists, but it ranks last in its rate per 100,000 population. Nevada's population is 1.7 million. Its rate is
			A)	35
			B)	42
			C)	29
			D)	Do not know
5			Last year, there were 4 million live births in the United States. The national birth rate per 1,000 population (total population: 274 million)
			A)	16.8
			B)	37.2
			C)	14.6
			D)	Do not know
6			Maine's birth rate was the lowest in the nation. There were 13, 775 births for its population of 1,240,000. Its rate was
			A)	15
			B)	12.6
			C)	11.1
			D)	Do not know
7			Utah's birth rate was the highest in the nation. There were 41,390 births for a population of 2 million. The rate was
			A)	20.7
			B)	29.5
			C)	22.2
			D)	Do not know
8			A house assessed at $77,350 in a community with a property tax of $8.50 per hundred dollars of valuation will have a property tax bill of
			A)	$6,574.75
			B)	$657.48
			C)	$9,100
			D)	Do not know
9			In a recent year, there were 28,000 infant deaths among the 3,900,000 who were born that year, an infant mortality rate of 7.2 deaths per 1,000 live births. Alabama's infant mortality rate ranked first in the country that year. It had 631 infant deaths for 61,477 births, a rate of
			A)	11.3
			B)	12.7
			C)	10.3
			D)	Do not know
10			In the same year, California's rate was the lowest, although it had more infant deaths than any other state, 3,287. It had 539,800 live births during the year. Its infant mortality rate was
			A)	7.2
			B)	6.1
			C)	6.6
			D)	Do not know