Time and Work – LCM Method and Efficiency Tricks
Solve time and work problems quickly using LCM method and efficiency concepts.
Core Concept
Work = Time × Efficiency
LCM Method Trick
Example: A completes work in 10 days, B in 15 days
Step 1: LCM of 10 and 15 = 30
Efficiency:
A = 30/10 = 3 units/day
B = 30/15 = 2 units/day
Together:
3 + 2 = 5 units/day
Total Time:
30 ÷ 5 = 6 days
Shortcut Trick
Formula:
(A × B) / (A + B)
Example:
10 × 15 / (10 + 15) = 150/25 = 6 days
Efficiency Concept
If A is twice as efficient as B, then:
A : B = 2 : 1
Time ratio = 1 : 2
Exam Level Questions
1. A completes work in 8 days, B in 12 days → together?
Answer: 24/(3+2) = 4.8 days
2. A alone takes 20 days, works 5 days → work done?
Answer: 5/20 = 1/4
3. A:B efficiency = 3:2 → time ratio?
Answer: 2:3
Common Mistake
Students calculate directly instead of using LCM method.
Speed Tip
Always convert time into efficiency using LCM for faster solving.
Speed Maths • Bank Exam Preparation
No comments:
Post a Comment