As we have noted in previous chapters, even a very small effect can be significant if the sample is large enough. For each of the following, determine how large a sample is necessary for the correlation to be significant. Assume a two-tailed test with α = .05. (Note: The table does not list all the possible df values. Use the sample size corresponding to the appropriate df value that is listed in the table.)
a. A correlation of r = 0.30.
b. A correlation of r = 0.25.
c. A correlation of r = 0.20.