The accompanying data refers to concentration of the radioactive isotope strontium-90 in milk samples obtained from five randomly selected dairies in each of four different regions.

1 6.4 5.8 6.5 7.7 6.1 Region 2 7.1 9.9 11.2 10.5 8.8 3 5.7 5.9 8.2 6.6 5.1 4 9.5 12.1 10.3 12.4 11.7 Test at level .10 to see whether true average strontium-90 concentration differs for at least two of the regions.