A veterinary technician is designing an X-ray development unit. To prevent radiation, the walls must be at least 2 5/8 inches thick if gypsum sheet rock is used or 1/16 inch thick if lead is embedded. What is the difference in thickness between the two walls?

A veterinary technician is designing an X-ray development unit. To prevent radiation, the walls must be at least 2 5/8 inches thick if gypsum sheet rock is used or 1/16 inch thick if lead is embedded. What is the difference in thickness between the two walls?

• A. 2 3/4 inches
• B. 2 9/16 inches
• C. 3 inches
• D. 2 1/2 inches

Answer: (B)

The concept here is subtracting two mixed-number measurements by using a common denominator. To find the difference between 2 5/8 inches and 1/16 inch, convert to sixteenths: 2 5/8 equals 2 10/16. Subtract 1/16 to get 2 9/16 inches. So the difference is 2 9/16 inches (which is 2.5625 inches in decimal form). This is larger than 2 1/2 but less than 2 11/16, and matches the given difference.

The concept here is subtracting two mixed-number measurements by using a common denominator. To find the difference between 2 5/8 inches and 1/16 inch, convert to sixteenths: 2 5/8 equals 2 10/16. Subtract 1/16 to get 2 9/16 inches. So the difference is 2 9/16 inches (which is 2.5625 inches in decimal form). This is larger than 2 1/2 but less than 2 11/16, and matches the given difference.