A Fitness Centre Employs 4 Different Fitness Instructors

Essay

A fitness centre employs 4 different fitness instructors. Management would like to investigate if the different fitness instructors are getting different results with their team members.
The number of kilograms lost per member over the last twelve months is recorded and divided by fitness instructor they were using.
A table of fitness instructors with kilograms lost by each individual member, is given below.
Can you advise management if the fitness instructors are consistent, (ie: test that at least two populations differ), at the 5% level of significance. $$\begin{array} { | c | c | c | c | } \hline { \text { Fitness instructor } } \\\hline \mathrm { A } & \mathrm { B } & \mathrm { C } & \mathrm { D } \\\hline 13 & 15 & 18 & 9 \\\hline 9 & 10 & 15 & 10 \\\hline 16 & 15 & 17 & 6 \\\hline 12 & 14 & 18 & 6 \\\hline 15 & & 13 & \\\hline 8 & & & \\\hline\end{array}$$