6. The difference between the groups is:

(a) Unlikely to have occurred by sampling error, assuming the null hypothesis to be true

(F (2,470) = 387.806; p 6 0.001)

(b) Unlikely to have occurred by sampling error, assuming the null hypothesis to be true

(F (2,470) = 14.565; p 6 0.001)

(c) Likely to have occurred by sampling error, assuming the null hypothesis to be true

(F (2,470) = 387.806; p 6 0.001)

(d) Likely to have occurred by sampling error, assuming the null hypothesis to be true

(F (2,470) = 14.565; p 6 0.001)