Math Tools, Chapters 9-12

Directional Measurements

Though deadlines are often looming and journalists typically aren’t the first ones to take the initiative to do a math problem, checking numbers dealing with time, rate and abacus-1866497_1280.jpgdistance can be a crucial step to ensuring an accurate story. There are simple formulas reporters can follow to check math in these situations — and most only require basic multiplication and division.

Distance = rate x time

Rate = distance ÷ time

Time = distance ÷ rate

Example problem 1

Your mother is coming to visit for the weekend! You need to pick her up from Raleigh-Durham airport in the morning, which is 55 miles away from Elon University. If you plan to leave your dorm at 9 a.m., how fast must you drive to get there by 9:50 a.m., when her flight arrives?

Rate = 55 miles ÷ .85 hours = 64.7 or about 65 mph

Speed

Though our cars’ speedometers show us instantaneous speed, it is more useful for reporters to know how to calculate average speed.

Average speed = distance ÷ time

Example problem 2

Alexa came in fourth on her team at their cross country meet. Her 5K (3.1 miles) time was 24:29. What was her average speed during the race?

Average speed = 3.1 miles ÷ 24:29 =

3.1 miles ÷ .4 hours = 7.75 mph

Area Measurements

Being able to clearly express measurements is an important skill for journalists to have. Sometimes these illustrations take on the form of analogies, such as likening the square footage of the new superstore to that of a football, and other time actual numbers and specific figures are required to clearly describe measurements.

Articles about construction projects will invariably require you to report on perimeter and area.

For a square or a rectangle shaped structure:

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

For irregular shapes, simply add the lengths of all the sides to find the perimeter.

calculator-983900_1280.jpgExample problem 3

Your uncle is landscaping his backyard and decided to include a brick, pentagonal-shaped patio. The sides vary in length. If the base is five feet, the two sides are each seven feet, and the top edges are each five feet, what is the perimeter?

5+6+6+7+7 = 36 feet

For a square or a rectangle shaped structure complete the following formulas:

Area = length x width

For a triangular shaped structure:

Area = .5 base x height

Volume measurements

liquid conversion

Example problem 4

You bought four quarts of ice cream from a local fundraiser. How many servings will the ice cream yield if each serving is approximately one cup?

4 quarts = 128 ounces

128 ounces ÷ 8 ounces = 16 servings

Volume of rectangular solid = length x width x height

The metric system

Metric Volumes

Though in the states, many people are intimidated by the system of measurement, converting from one unit to another within the metric system requires only multiplying and dividing by 10, 100, 1,000 or other multiples of 10.

 

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