NCCER Core Introduction to Construction Math 2 — Questions and Answers
Question 1: What is the result of adding 3/8 and 5/8?
- 8/16
- 1
- 8/8
- Both B and C (Correct answer)
Correct answer: Both B and C
3/8 + 5/8 = 8/8 = 1. Both 8/8 and 1 are the same value.
With a common denominator: (3+5)/8 = 8/8 = 1. This type of calculation occurs frequently when adding measurements from a tape measure, such as combining material thicknesses.
Question 2: A board is 96 inches long. How many feet is that?
- 6 feet
- 7 feet
- 8 feet (Correct answer)
- 9 feet
Correct answer: 8 feet
96 / 12 = 8 feet.
96 / 12 = 8 feet, corresponding to the standard 8-foot lumber length. Standard lumber lengths are 8', 10', 12', 14', 16', 18', and 20'. The single tick (') = feet; double tick (") = inches.
Question 3: What is 25% of 200 linear feet of lumber?
- 25 feet
- 50 feet (Correct answer)
- 75 feet
- 100 feet
Correct answer: 50 feet
25% of 200 = 0.25 x 200 = 50 feet.
25% = 0.25, and 0.25 x 200 = 50 feet. Percentages are used for waste factors (10-15% extra), sales tax, slope calculations (2% grade = 2 feet per 100 feet), and progress billing.
Question 4: What unit measures the cross-sectional area of electrical wire?
- Square inches
- Circular mils (Correct answer)
- Linear feet
- Board feet
Correct answer: Circular mils
Circular mils (CM) express the cross-sectional area of electrical wire.
A circular mil is the area of a circle with a 1 mil (0.001 inch) diameter. Wire size uses AWG, but cross-sectional area is in circular mils. Example: 12 AWG = 6,530 cmil. Larger wires use kcmil. Wire ampacity is directly related to cross-sectional area.
Question 5: What is the area of a triangle with base 10 feet and height 6 feet?
- 60 sq ft
- 30 sq ft (Correct answer)
- 16 sq ft
- 36 sq ft
Correct answer: 30 sq ft
Area = 1/2 x 10 x 6 = 30 square feet.
A = 1/2 x b x h. Important for gable end areas, triangular roof sections, and cut material pieces. The formula applies regardless of triangle type as long as height is perpendicular to the base.
Question 6: A pipe drops 1/4 inch per foot over a 20-foot run. What is the total drop?
- 2.5 inches
- 5 inches (Correct answer)
- 10 inches
- 20 inches
Correct answer: 5 inches
1/4 inch/foot x 20 feet = 5 inches.
Drainage slope ensures proper water flow. IPC minimum slopes: 1/4"/ft for pipes 3" or smaller, 1/8"/ft for 4"+ pipes. Insufficient slope causes standing water; excessive slope can cause liquids to outrun solids, both causing clogs.
NCCER Core Introduction to Construction Math 2
What is the result of adding 3/8 and 5/8?