NCCER Core Construction Math Fundamentals 3 — Questions and Answers
Question 1: Convert 3.75 feet to feet and inches.
- 3 feet 6 inches
- 3 feet 9 inches (Correct answer)
- 3 feet 7.5 inches
- 3 feet 8 inches
Correct answer: 3 feet 9 inches
0.75 feet x 12 = 9 inches. So 3.75 feet = 3 feet 9 inches.
Multiply the decimal portion by 12: 0.75 x 12 = 9 inches. Common equivalents: 0.25 ft = 3", 0.5 ft = 6", 0.75 ft = 9". This conversion is needed when using a calculator and then measuring with a tape.
Question 2: A room requires 180 sq ft of tile. If tiles come in boxes of 20, how many boxes are needed?
- 8 boxes
- 9 boxes (Correct answer)
- 10 boxes
- 11 boxes
Correct answer: 9 boxes
180 / 20 = 9 boxes.
Each 1'x1' tile covers 1 sq ft, so 180 tiles needed. 180 / 20 = 9 boxes. In practice, add 10-15% for waste (cuts, breakage), meaning 10-11 boxes.
Question 3: What is the perimeter of a 30 ft by 50 ft rectangular foundation?
- 1,500 feet
- 80 feet
- 160 feet (Correct answer)
- 120 feet
Correct answer: 160 feet
Perimeter = 2(50 + 30) = 2(80) = 160 feet.
P = 2(L + W) = 2(30 + 50) = 160 feet. Perimeter calculations are used for ordering linear materials such as foundation forms, baseboard, crown molding, fencing, and perimeter drainage.
Question 4: How many cubic yards of concrete are needed for a 20 ft x 30 ft x 4 inch slab?
- 5.4 cubic yards
- 7.4 cubic yards (Correct answer)
- 9.2 cubic yards
- 11.1 cubic yards
Correct answer: 7.4 cubic yards
4 inches = 0.333 ft. Volume = 20 x 30 x 0.333 = 200 cu ft. 200 / 27 = 7.4 cubic yards.
Convert 4" to feet: 4/12 = 0.333 ft. Volume = 20 x 30 x 0.333 = 200 cu ft. Convert to cubic yards: 200 / 27 = 7.41. Order about 8 cubic yards for subgrade irregularities and waste.
Question 5: What is 5 feet 8 inches plus 3 feet 7 inches?
- 8 feet 15 inches
- 9 feet 3 inches (Correct answer)
- 8 feet 3 inches
- 9 feet 1 inch
Correct answer: 9 feet 3 inches
Feet: 5 + 3 = 8. Inches: 8 + 7 = 15. Convert: 15" = 1' 3". Total: 9 feet 3 inches.
Add separately: 5 + 3 = 8 ft, 8 + 7 = 15 in. Since 15 > 12, convert: 15 - 12 = 3" with 1 extra foot. 8 + 1 = 9 ft. Answer: 9 feet 3 inches.
Question 6: A staircase must rise 108 inches. With 7.5-inch risers, how many risers are needed?
- 12
- 14 (Correct answer)
- 15
- 16
Correct answer: 14
108 / 7.5 = 14.4, rounded to 14 risers with slight adjustment to riser height.
108 / 7.5 = 14.4. Round to 14 risers: 108/14 = 7.714" per riser. Or 15 risers: 108/15 = 7.2" per riser. Both within IRC code range. Number of treads is always one less than risers.
NCCER Core Construction Math Fundamentals 3
Convert 3.75 feet to feet and inches.