Which of the following represents an exact quantity? A) There are 2.54 cm in an inch. B) A man is 5 feet 10 inches tall. C) A man weighs 200 lb. D) It takes 15 minutes to drive to the grocery store. E) There are 80 grams of sugar in a serving of soda.
The Correct Answer and Explanation is:
The correct answer is A) There are 2.54 cm in an inch.
Explanation:
An exact quantity refers to a value that is defined with no uncertainty or error. It is often based on a definition or a universally agreed-upon standard.
- A) There are 2.54 cm in an inch: This is an exact conversion factor. The value of 2.54 cm per inch is defined by international agreement and is not subject to any variation. It is based on the definition of the inch and centimeter units as per the metric system, and this conversion is universally recognized.
- B) A man is 5 feet 10 inches tall: This is a measured quantity, and therefore not exact. There is some uncertainty inherent in measuring someone’s height, depending on the precision of the measurement tools and the method of measurement.
- C) A man weighs 200 lb: This is also a measured quantity, as weight is subject to variability based on factors like scale accuracy, body composition, and environmental conditions. It is not an exact value.
- D) It takes 15 minutes to drive to the grocery store: The time it takes to drive is a measured quantity, which depends on traffic, speed, and road conditions. It is not an exact quantity and can vary.
- E) There are 80 grams of sugar in a serving of soda: While this might seem like an exact quantity, it is still a measured quantity, as the sugar content can vary depending on the brand, formulation, or even batch of soda.
In summary, A is the only option representing an exact quantity, as it is a fixed conversion defined by international standards.
