Jambmaths question:
The time taken to a piece of work is inversely proportional to the number of men employed. If it takes 45 men to do a piece of work in 5 days, how long will it take 25 men?
Option A:
15 days
Option B:
12 days
Option C:
5days
Option D:
9days
Jamb Maths Solution:
$\begin{align} & \text{Let }t\text{ be the time taken} \\ & \text{Let }m\text{ the number of men} \\ & t\propto \frac{1}{m} \\ & t=\frac{k}{m}\text{ (}k=proportionality\text{ }constant) \\ & \text{when }m=45,\text{ }t=5 \\ & 5=\frac{k}{45} \\ & k=225 \\ & \text{When we have 25 men, the number of days will be} \\ & t=\frac{k}{m}=\frac{225}{25} \\ & t=9days \\\end{align}$
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