Two conveyor belts deliver baggage at constant rates. Belt 1 delivers 3 tonnes in 5 minutes; Belt 2 delivers 1 tonne in 2 minutes. If both belts run together, how long will it take to deliver 33 tonnes?
Aptitude
Time and Work
Difficulty: Easy
Choose an option
Answer
Correct Answer: 30 min
Explanation
Introduction / Context:When two sources deliver together, their rates add. Convert both to tonnes per minute, add them, and divide the target tonnage by the combined rate.
Given Data / Assumptions:
- Belt 1: 3 t in 5 min ⇒ 0.6 t/min.
- Belt 2: 1 t in 2 min ⇒ 0.5 t/min.
- Total required = 33 t.
Concept / Approach:Combined rate r = 0.6 + 0.5 = 1.1 t/min. Time = quantity / rate.
Step-by-Step Solution:
r = 1.1 t/min.Time = 33 / 1.1 = 30 minutes.Verification / Alternative check:In 30 minutes, they deliver 30 * 1.1 = 33 t, exactly matching the target.
Why Other Options Are Wrong:25:30, 35, 40:45, 28 min do not yield exactly 33 t with the given rates.
Common Pitfalls:Using minutes per tonne (instead of tonnes per minute) and mis-inverting the result; rounding mid-calculation.
Final Answer:30 min