The pie-charts below give the percentage distribution of employees in different Departments in XYZ Company Ltd. during the years 2005 and 2006. A - Administration; B - Operations; C - Sales & Marketing; D - Finance & Accounts; E - Corporate HQ.
2005 (total employees 18,000): A 22%, B 23%, C 18%, D 29%, E 8%.
2006 (total employees 20,000): A 24%, B 26%, C 20%, D 20%, E 10%.
If 300 employees left Operations at the end of 2005, how many joined in 2006?
Show Hint
Work out Operations' headcount for 2005 and 2006 from the pie charts, subtract to get the net change, then add back the 300 who left since new joiners must cover both the net growth and the departures.
Think of this as a flow of people rather than a formula. Operations had 4,140 employees at the start of 2005 (from $23\% \times 18000$). At the end of 2005, 300 of them left, so only $4140 - 300 = 3840$ of the original group carried over into 2006 as "surviving" staff.
By the end of 2006, Operations has $26\% \times 20000 = 5200$ employees, from the pie chart.
Of these 5200, only 3840 are people who were already there and stayed on; everyone else must be a fresh joiner during 2006.
Number of fresh joiners $= 5200 - 3840 = 1360$.
This "who is still around" way of thinking gives the same figure as adding the net increase to the number who left, because 1,060 (net increase) plus 300 (attrition) is exactly 1,360.
Let's summarize:
Track people as a running total: start, minus leavers, plus joiners, equals end.
A net increase in headcount can hide a much larger number of new joiners if there was also attrition to make up for.
1,360 employees joined the Operations department in 2006.
