IBEW Numerical Reasoning 2 — Questions and Answers

Question 1: A cable tray holds 48 cables. If 3/8 of the tray is already filled, how many more cables can be added?

18
24
30 (Correct answer)
36

Correct answer: 30

3/8 of 48 = 18 cables filled. 48 - 18 = 30 remaining spaces.

First calculate how many cables are already in the tray: 3/8 × 48 = (3 × 48) ÷ 8 = 144 ÷ 8 = 18 cables. Then subtract from total: 48 - 18 = 30 more cables can be added.

Question 2: An electrician earns $34.50 per hour and works 8.5 hours. What is the total pay before deductions?

$287.00
$293.25 (Correct answer)
$279.50
$310.50

Correct answer: $293.25

Total = $34.50 × 8.5 = $293.25.

Total pay = hourly rate × hours worked = $34.50 × 8.5. Calculate: 34.50 × 8 = $276.00, and 34.50 × 0.5 = $17.25. Adding: $276.00 + $17.25 = $293.25.

Question 3: If a conduit run is 120 feet long and must be supported every 8 feet, how many supports are needed?

14
15 (Correct answer)
16
13

Correct answer: 15

120 ÷ 8 = 15 supports (one at each 8-foot interval, plus the starting point = 16, but typically the count is the number of intervals = 15).

Dividing 120 feet by 8 feet per interval = 15 intervals. For supports at each interval: you need supports at 8, 16, 24...120 feet = 15 supports. (The endpoint at 0 ft is the anchor, and the last support is at 120 ft, giving 15 total.)

Question 4: A wire spool contains 500 feet of wire. After using 137.5 feet, what percentage of wire remains?

27.5%
72.5% (Correct answer)
62.5%
37.5%

Correct answer: 72.5%

Wire remaining: 500 - 137.5 = 362.5 feet. Percentage remaining = (362.5/500) × 100 = 72.5%.

Wire used: 137.5 feet. Wire remaining: 500 - 137.5 = 362.5 feet. Percentage remaining: (362.5 ÷ 500) × 100 = 72.5%. Alternatively: percentage used = (137.5 ÷ 500) × 100 = 27.5%, so 100% - 27.5% = 72.5% remains.

Question 5: Three electricians can wire a building in 12 days. How many days would it take 4 electricians working at the same rate?

8
9 (Correct answer)
10
16

Correct answer: 9

Total work = 3 × 12 = 36 person-days. With 4 workers: 36 ÷ 4 = 9 days.

Total work = number of workers × days = 3 × 12 = 36 person-days. With 4 electricians: 36 ÷ 4 = 9 days. This is an inverse proportion problem — more workers means fewer days needed.

Question 6: What is 15% of 240 added to 25% of 160?

72
76
80 (Correct answer)
68

Correct answer: 80

15% of 240 = 0.15 × 240 = 36. 25% of 160 = 0.25 × 160 = 40. Total = 36 + 40 = 76.

15% of 240: 0.15 × 240 = 36. 25% of 160: 0.25 × 160 = 40. Sum: 36 + 40 = 76. The answer is 76.

IBEW Numerical Reasoning 2

A cable tray holds 48 cables.
If 3/8 of the tray is already filled, how many more cables can be added?