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A parent theorized that his daughter spent more time on her cell phone than his son. He randomly selected 27 calls made by his son and 25 call made by his daughter from his past phone records. His son’s calls had an average length of 23.5 minutes with a variance of 28 minutes. While his daughter’s calls had an average length of 36.1 minutes with a variance of 35 minutes. Find the 99% confidence interval for the true mean difference between the length of calls made by his son and his daughter (Do not assume equal variances). Is there a significant difference?