correlation between group/factor level & individual scores with group means and MSE

Hi everyone,

I've been working on this problem for a couple hours now, and I'm stumped.

Essentially what we have are 4 groups of 25 people each. The groups are formed around a sales goal for each group ($10k, $20k, $30k, $40k). We don't know the individual scores within those groups, but we have 4 group means (15.5, 16.2, 17.9, 20). We've also been given a Mean Square Error (40). The question asked is what is the correlation between the individual scores in the group and the sales goal of the groups. Originally my thinking was to multiply each group mean by 25 to get a group score, then find the correlation (using R), but that correlation gives me the same answer as the correlation between the means and the sales goals (which the question specifically says is not what is wanted).

Would very much appreciate any thoughts. Thanks.