## Posts filed under ‘Math Tools’

### Helpful math tips for journalists: ‘Math Tools for Journalists’ chapters 9-12

By Patrick McCabe

Written May 12, 2009

**Directional Measurements**

**Time, Rate and Distance**

When working with time, rate and distance problems the most important thing is to keep the units of measurement the same.

If the rate is in miles per hour then the distance needs to be miles and the time needs to be hours. If anything is not the same it should be converted.

FORMULAS:

Distance= rate x time

Rate= distance/time

Time= distance/rate

**Speed, velocity, acceleration, g-force and momentum**

Speed and velocity are different. Speed measures how fast something is going while velocity indicates its direction. Acceleration measures how quickly something speeds and g-force is an acceleration measure. The “g” represents the normal force of gravity. Momentum is the force needed to stop an b=object in motion.

FORMULAS AND EXAMPLES:

Acceleration=(ending velocity – starting velocity)/time

If a car accelerates from s=zero to 60 in 30 seconds what is the rate of acceleration?

(60 mph – 0 mph)/30 seconds = 2mph per second

Momentum= mass x velocity

What was the momentum of a race car weighing 132 kilograms when it crashed into a wall if it traveling 150 mph?

Convert mph to kilometers per hour (kph): 105 mph x 1.6= 168kph

132 kilograms x 168 kph= 22,176 kilogram kilometers per hour

**Area Measurements**

Journalists can use area measurements in all different types of stories. It is useful for a journalist to know how to calculate perimeter when writing articles about new developments or construction projects. Area is also important for real estate, technical, feature and sports reports. Square feet and square yards are useful when checking reports on size and circumference and radius are important for dealing with stories on circular area.

FORMULAS:

Perimeter = (2 x length) + (2 x width)

Area (squares and rectangles) = length x width

Area (triangles) = .5 base x height

Circumference = 2P x radius

Area (circles) = 2P x (radius)^2

**Volume Measurements**

In the business world terms like ton, barrel, box and cord take on a specific meaning. Goods are often sold in volumes. A goods measurement can vary based on the market, knowing how to measure volume is a key component to selling any good.

**Liquid Volume**

Liquid measurements apply to liquids in recipes, bodies of water and other fluids.

EXAMPLES:

2 tablespoons = 1 fluid once

4 quarts = 1 gallon

1 U.S. standard barrel = 31.5 gallons

For finding the volume of a rectangular solid use this formula: Volume = length x width x height

Other measurements:

Cord: 128 cubic feet

Ton:

Short ton= 2,000 lbs

Long ton= 2,240 lbs

Metric ton= 2,204.62 lbs

**The Metric System**

Most Americans struggle to use the metric system yet the rest of the world uses it for every type of measurement. The metric system is an important tool for international commerce. It is based on the multiples of 10.

**Definitions**

Meter: basic unit for length

Mass: derived from meter and the unit for weight

Newton: unit of force

**Basics**

Because the metric system is based on the decimal system you can change from one unit to another simply by multiplying or dividing by any multiple of ten. Each unit is ten times as large as the next unit.

Prefixes can create larger or smaller factors when added to a unit name. The prefixes for numerical values are:

micro (1 millionth) 0.000001

milli (1 thousandth) 0.001

centi (1 hundredth) 0.01

deci (1 tenth) 0.1

no prefix 10

deka 10

hecto 100

kilo 1,000

mega 1,000,000

giga 1,000,000,000

tera 1,000,000,000,000

For a more in-depth explanation of the metric system click here.

### Math Tools for Journalists: Chapters 5-8

How a journalist should analyze polls, surveys, business, stocks and bonds and property taxes.

By Patrick McCabe

No one, not even journalists can escape the math world. Math is a great tool for a journalist to present cold hard facts using numbers and journalists use a variety of math tools in their pieces.

**Polls and Surveys **

While both polls and surveys are based on representative samples of a population polls are an estimate of public opinion based on one question or topic that is being presented while surveys look at variety of questions.

When evaluating polls remember the following:

- Name and background of polling organization
- Who paid for the poll
- How and when the poll was conducted
- The exact wording of the question asked
- The size of the sample and response rate
- The sample method
- The margin of error
- The relationship recent events may have had on the poll results

Remember these tips will help any reporter who chooses to use polls when reporting on a story. These tips can also help a reporter using samples but they should remember that a sample looks to represent a population while a poll aims for approximately 400 participants.

**Business**

The world of business often produces major news and is chalked full of math. Examples of business news include financial statements, profit and loss statements, balance sheets and ratio analysis. These documents provide a number of tools journalists can use when reporting on a businesses financial status or big financial endeavors.

Tips for dealing with financial statements:

- Numbers are often written in “thousands” or millions,” deleting the last zeros. Watch out for this because it can trick you.
- Figures in parentheses are negative.
- Compare net figures over time, it is more newsworthy to report changes over time than to report one years numbers.

These tips will help you analyze financial statements that are trying to trick a ill informed reporter.

**Stocks and Bonds**

Stocks and bonds are how most businesses make money. Bonds are also used by the government to raise funds. Understanding these money making tools is important for all journalists.

Stocks are sold by companies to share holders. Once a share holder is in possession of stock they become a part owner in the company but because there are so many stocks sold each year shareholders often represent a tiny portion of ownership.

Stocks change worth overtime. The more people want a stock the higher its price will go and the higher the shareholders worth will be. Mutual funds are also an option for stock enthusiasts but mutual funds invest in a variety of companies with a “mutual” interest as opposed to one specific company.

A bond is simply a loan form an investor to the government or other selling organization that earns interest over a period of time. Bonds are generally low-risk investments.

The bond owner pays “face value” for a bond and receives an annual interest rate. At the completion of the bond the owner will also receive the face value.

FOR EXAMPLE:

A bond is purchased for $1,000 with a 5 percent interest rate and a maturity date of 30 years. The bond owner will receive $50 each year and after 30 years will receive the $1,000 face value.

Bonds can be tricky because their value fluctuates with supply and demand.

**Property Taxes**

Property taxes are the largest source of income for local government, school districts and other municipal organizations. A property tax rate is determined by taking the total amount of money the government needs and dividing that by the total number of property owners. How much each owner pays is based on the value of their property. While most districts only take into account real property like real estate, homes and buildings, some also tax valuable assets.