BARB Work Rate 2

Question 1

Soldier A can complete a task in 6 hours alone. Soldier B can complete the same task in 3 hours alone. How long will they take working together?

Accepted Answer

2 hours

Answer

A's rate = 1/6, B's rate = 1/3; Combined = 1/6 + 2/6 = 3/6 = 1/2 task per hour; Time = 2 hours.

Question 2

A factory produces 500 units in 10 hours. How many units are produced in 7 hours?

Accepted Answer

350

Answer

Rate = 500 ÷ 10 = 50 units/hr; In 7 hrs = 50 × 7 = 350 units.

Question 3

Three engineers each repair 8 vehicles per day. How many vehicles do they repair in 5 days?

Accepted Answer

120

Answer

Daily total = 3 × 8 = 24 vehicles; Over 5 days = 24 × 5 = 120 vehicles.

Question 4

A soldier completes 1/4 of a task each hour. How long does the full task take?

Accepted Answer

4 hours

Answer

If 1/4 is done per hour, the full task takes 4 hours.

Question 5

Worker A completes a job in 8 hours and Worker B completes the same job in 4 hours. How long do they take working together?

Accepted Answer

2 hours 40 min

Answer

A's rate = 1/8, B's rate = 1/4 = 2/8; Combined = 3/8 per hr; Time = 8/3 ≈ 2 hrs 40 min.

BARB - British Army Recruit Battery Practice Test