Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
If 5 workers can build a wall in 12 days, how many workers are needed to build it in 4 days?
10
12
15
20
15
Since the time is reduced to one-third (from 12 to 4), the number of workers must increase by three times: 5├Ч3=15.
Number of workers (W1) = 5, Time taken (D1) = 12 days, Target time (D2) = 4 days.
M1тАЛ├ЧD1тАЛ=M2тАЛ├ЧD2тАЛ
Since the time is reduced to one-third (from 12 to 4), the number of workers must increase by three times: 5├Ч3=15.
Students often use direct proportion (5/12 = x/4), which is incorrect because workers and time are inversely proportional.
Identify Relationship
Since the total work is constant, the number of workers is inversely proportional to the time taken.
Work=Workers├ЧDays
Apply Formula
Substitute the given values into the inverse proportion formula M1тАЛ├ЧD1тАЛ=M2тАЛ├ЧD2тАЛ.
5├Ч12=M2тАЛ├Ч4
Calculate Result
Solve for M2тАЛ by dividing the total work by the target days.
M2тАЛ=45├Ч12тАЛ=15
C is correct because the calculation shows that 15 workers are required to complete the work in 4 days.
This concept of inverse variation is identical to the Pipe and Cistern problems where efficiency is inversely proportional to time.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download тАв 100K+ Aspirants