6400 workers were employed to construct a factory in 4 years. A the end of the first year, 25% workers were retrenched. At the end of the second year, 25% of those working at that time were again retrenched. However, to complete the project in time, the number of workers was increased by 25% of the total number of workers left at the end of third year. How many workers were working during the fourth year ?

Explanation

Number of workers at the beginning = `6400`
Period = `4` years
At the end of 1st year, workers retrenched =`25%`
At the end of second year, workers retrenched =`25%`
At the end of third year, workers increased =`25`%
Total number of workers during the `4` years
`6400(1-25/100)(1-25/100)(1+25/100)`
=`4500`.