This problem can be solved by treating it like a
weighted average prooblem.
Let the average number of holidays/employee be x (the weighted average).
From the stem we know that the average number of holidays/CFA = x-5 and the average number of holidays/MBA = x+10.
Apppying the
teeter totter method (from MGMAT): Thus, the the total distance between x-5 and x+10 = 15.
x-5--------------------x-----------------------x+10
distance from x=5 , distance from x=10
As we want to determine the number of CFAs, we can use the above teeter totter to conclude CFAs make up \(\frac{10}{15}=\frac{2}{3}\)of the total number of employees.
Using the teeter totter is a great way to simplify and visualise. Moreover, this approach is quite fast and took me around 1.5 minutes.
Please hit Kudos if you liked this approach