[4. A 2008 survey of low and middle-income households conducted by Demos, a liberal public group, showed that consumers aged 65 years and older had an average credit card debt of $10,550 and consumers in the 50 to 64year age group had an average credit card debt of $9650 at the time of the survey (USA TODAY, July 28, 2009}. Suppose that these averages were based on random samples of 1000 and 1200 people for the two groups, respectively. Further assume that the population standard deviations for the two groups were $2400 and $2200, respectively. Let [.11 and p2 be the respective population means for the two groups, people aged 65 years and older and people in the 50- to 64-year age group. (3) Calculate the point estimate of for ul p2. (bl Construct a 98% confidence interval for .41 '12 mentioning its formula and interpret the result. This Fnrl 2 4