IBEW Ratio and Proportion 2

Question 1

If mixing a solution requires a 3:1 ratio of water to chemical concentrate, how many gallons of concentrate are needed for 12 gallons of total solution?

Accepted Answer

3 gallons

Answer

In a 3:1 ratio the total is 4 parts, so concentrate is 1/4 of 12 gallons = 3 gallons.

Question 2

A motor runs at 1,800 RPM and is connected by a belt to a pulley with a 3:1 drive ratio. What is the output RPM of the driven pulley?

Accepted Answer

600 RPM

Answer

A 3:1 drive ratio means the driven pulley turns at 1,800 ÷ 3 = 600 RPM.

Question 3

Two gears mesh together. The drive gear has 48 teeth and the driven gear has 16 teeth. If the drive gear rotates at 200 RPM, how fast does the driven gear rotate?

Accepted Answer

600 RPM

Answer

The gear ratio is 48:16 = 3:1, so the smaller driven gear rotates at 200 × 3 = 600 RPM.

Question 4

An electrician earns $28 per hour and works 8 hours per day. At the same daily rate, how much does he earn in 5 days?

Accepted Answer

$1,120

Answer

Daily earnings are $28 × 8 = $224, so for 5 days: $224 × 5 = $1,120.

Question 5

If a 3/4-inch conduit can hold 12 wires, how many wires can a 1.5-inch conduit (twice the diameter) hold, assuming capacity scales with the square of the diameter?

Accepted Answer

48

Answer

When diameter doubles, area quadruples (2² = 4), so capacity is 12 × 4 = 48 wires.

IBEW - Aptitude Test Practice Test

IBEW - Aptitude Test Practice Test

IBEW Ratio and Proportion 2