A marketing study found that the mean spending in 15 categories of consumer items for 297 respondents in the 18–34 age group was $71.86 with a standard deviation of $70.90. For 736 respondents in the 35+ age group, the mean and standard deviations were $61.53 and $45.29, respectively. Develop 95% confidence intervals for the difference in mean spending amounts between each age group. What assumption did you make about equality of variances?