Two Sets of 95% Confidence Intervals Correspond to a Random

Multiple Choice

Two sets of 95% confidence intervals correspond to a random sample of two groups: group A: c.i. = 6.5 ± 0.5; group B: c.i. = 7.4 ± 0.2. Which of the following could we conclude about the mean differences of the groups with these confidence intervals?

A) There is a significant difference between the two populations' means (alpha = 0.05) .
B) There is no significant difference between the two populations' means (alpha = 0.05) .
C) The confidence intervals overlap, so there is likely a significant difference between the two populations' means.
D) We cannot conclude anything; the confidence intervals overlap, but the separate confidence intervals do not correctly pool the variance and sample size of the two groups.