The following table shows the number of employees and their median age in eight companies located in a district.
Company Number of employees Median age A 32 24 B 28 30 C 43 39 D 39 45 E 35 49 F 29 54 G 23 59 H 16 63
It is known that the age of all employees are integers. It is known that the age of every employee in A is strictly less than the age of every employee in B, the age of every employee in B is strictly less than the age of every employee in C, ..., the age of every employee in G is strictly less than the age of every employee in H.
The median age of employees across the eight companies is:
The following table shows the number of employees and their median age in eight companies located in a district.
| Company | Number of employees | Median age |
|---|---|---|
| A | 32 | 24 |
| B | 28 | 30 |
| C | 43 | 39 |
| D | 39 | 45 |
| E | 35 | 49 |
| F | 29 | 54 |
| G | 23 | 59 |
| H | 16 | 63 |
It is known that the age of all employees are integers. It is known that the age of every employee in A is strictly less than the age of every employee in B, the age of every employee in B is strictly less than the age of every employee in C, ..., the age of every employee in G is strictly less than the age of every employee in H.
The median age of employees across the eight companies is:
Entered answer:
Solution
Add up all the employees across the eight companies:
Since there are employees (an odd number), the median is at position:
When you have an odd number of values arranged in order, the exact middle one is at position .
Since every employee in is younger than every employee in , who are all younger than every employee in , and so on — all employees can be thought of as standing in a single line from youngest to oldest. We just need to find which company the rd person belongs to.
Using cumulative count:
| Company | Number of Employees | Cumulative Count | Positions Covered |
|---|---|---|---|
| st to nd | |||
| rd to th | |||
| st to rd | |||
| th to nd | |||
| rd to th | |||
| th to th | |||
| th to th | |||
| th to th |
The rd value falls in Company (since it lies between the th and nd positions).
Company has employees, so its median is the:
The rd employee overall is the th employee within — which is exactly 's median.
This means the rd employee's age is exactly the median age of Company , which is .
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IPMAT Indore 2019