Business Math in Action

Quality Time

We’ve all seen the little stickers on a new item of clothing that say something like, “Inspected by #64.” Does #64 sit at a table all day pulling on the arms of sweaters as they move past on a conveyer belt? While this person is certainly a quality-control technician, he or she is probably doing more than just testing for strength. Manufacturers have developed ways to ensure that every item they ship is durable, safe, and consistent. Each object must meet specific tolerances and standards set by its industry and by the governments where the item is produced and sold. Here are a few examples of the ways products are quality-tested before they reach your local shopping mall.

Clothing. The #64s of the world test sample garments for tear strength, steam strength, abrasion resistance, seam slippage, and colorfastness. Garments are also tested for their appearance, feel and fall, and special finishes such as flame-resistance or ability to withstand extreme cold. The textiles that the garments are made of are tested to make sure they don’t contain harmful levels of dye or other chemicals used to process the fabric.

Baseballs. The Major League has developed stringent standards for manufacturing baseballs. As each ball is completed, it is weighed, measured, and checked for blemishes. Then it is shipped to a central warehouse, where sample balls are measured for their coefficient of restitution (COR). In this test, the ball is shot from an air cannon at 85 feet per second, bounced against a wood surface, and then measured to determine the rebound speed. The rebound speed is divided by 85 (the delivery velocity) to calculate the COR. In order to pass the test, the balls must register a rebound of about 54%. They also must retain their shape after being subjected to a 65-pound force.

Tomatoes. They’re tested for color, size, shape, damage (splitting, insects, or mold), texture, taste, and hardness. Manufacturers test taste by measuring levels of sourness, sweetness, saltiness, and bitterness. Hardness is measured by a penetrometer, a simple tool that drops a small weight on the tomato and calibrates the depression it creates.

Perfume. How can a company quality-test something as subjective as scent? They begin by scrutinizing the purity and quality of the raw materials from which the scent is created. They monitor the accuracy of the formulas used to produce the perfume, so that every batch will smell exactly the same. Samples of the finished perfumes are kept at the manufacturer’s under controlled conditions so the chemists and perfumers can match future batches to existing samples.