IBEW Ratio and Proportion 1 — Questions and Answers
Question 1: A wire crew installs 240 feet of conduit in 6 hours. At the same rate, how many feet will they install in 9 hours?
- 300 feet
- 320 feet
- 360 feet (Correct answer)
- 400 feet
Correct answer: 360 feet
The rate is 240 ÷ 6 = 40 feet per hour, so in 9 hours they install 40 × 9 = 360 feet.
Question 2: If 4 electricians can wire 3 apartments in 2 days, how many apartments can 8 electricians wire in 2 days?
- 4
- 5
- 6 (Correct answer)
- 8
Correct answer: 6
Doubling the number of electricians doubles the output, so 8 electricians wire 3 × 2 = 6 apartments in the same 2 days.
Question 3: The ratio of copper wire to aluminum wire used on a job is 5:3. If 40 pounds of copper wire is used, how many pounds of aluminum wire are needed?
- 18 pounds
- 20 pounds
- 24 pounds (Correct answer)
- 30 pounds
Correct answer: 24 pounds
Setting up the proportion 5/3 = 40/x gives x = (40 × 3) / 5 = 24 pounds.
Question 4: A blueprint is drawn at a scale of 1 inch = 8 feet. If a room measures 3.5 inches on the blueprint, what is the actual length of the room?
- 24 feet
- 26 feet
- 28 feet (Correct answer)
- 32 feet
Correct answer: 28 feet
Multiply the blueprint measurement by the scale factor: 3.5 × 8 = 28 feet.
Question 5: On a job site, the ratio of journeymen to apprentices is 2:5. If there are 14 journeymen, how many apprentices are on the site?
- 28
- 30
- 35 (Correct answer)
- 40
Correct answer: 35
Setting up the proportion 2/5 = 14/x gives x = (14 × 5) / 2 = 35 apprentices.
Question 6: If a 12-volt battery is connected to a circuit with a current of 3 amps, and the voltage is increased proportionally to produce 5 amps, what is the new voltage?
- 15 volts
- 16 volts
- 20 volts (Correct answer)
- 24 volts
Correct answer: 20 volts
Using the proportion 12/3 = x/5, solving gives x = (12 × 5) / 3 = 20 volts.
Question 7: A spool of wire contains 500 feet and weighs 15 pounds. How much does a 200-foot section of the same wire weigh?
- 5 pounds
- 6 pounds (Correct answer)
- 7 pounds
- 8 pounds
Correct answer: 6 pounds
The unit rate is 15/500 = 0.03 lb/ft, so 200 feet weighs 200 × 0.03 = 6 pounds.
IBEW Ratio and Proportion 1
A wire crew installs 240 feet of conduit in 6 hours.
At the same rate, how many feet will they install in 9 hours?