statistics
posted by donna .
A company director took a sample of salaries of 13 employees in a big school during a certain time. she divided the wages into three groups according to the different jobs: teachers, assistants and coordinators as displayed in the table below. She wanted to find out whether or not the means of the salaries classified by the three jobs are significantly different. Let the level of significance be
(a) 5 % and
(b) 1 %.
Workers 1 2 3 4 5
Teachers 74 65 72 69 
Assistants 75 78 74 76 72
Coordinators 56 55 53 52 
Can someone please help me to solve this question. I tried setting a hypothesis but I don't know if that is correct. Do I have to compare means?
st.statistics

With only 13 employees, it would be best to use X^2 (Chisquare) test.
Ho: no diference
X^2 = ∑ (OE)^2/E, where O = observed frequency and E = expected frequency.
∑ = sum of all the cells.
E = (column total * row total)/grand total
df = n  1, where n = number of cells
Look up value in X^2 table in the back of your textbook.