10000 workers were employed to construct a river bridge In four years. At the end of first year, 10% workers were retrenched. At the end of the second year, 5% of the workers at that time were retrenched. However to complete the project in time, the number of workers was increased by 10% at the end of the third year. How many workers were working during the fourth year?

Explanation

Initially No of workers =`10000`
After 1st year 10% workers left
therefore No of workers after 1st year =`10000−10000** 10/100 =9000`
After the 2nd year 5% worker left
therefore No of worker after 2nd year =`9000−9000** 5/100 =8550`
After 3rd year 10% worker increase
therefore No of worker after 3rd year =`8550+8550**10/100 =9405`
So the at the end of 4th year no of workers =`9405`