The cruise ship business is rapidly increasing. Although cruises have long been associated with seniors, it now appears that younger people are choosing a cruise as their vacations. To determine whether this is true, an executive for a cruise line sampled passengers 2 years ago and this year and determined their ages.,a. Do these data allow the executive to infer that cruise ships are attracting younger customers?,b. Estimate with 99% confidence the difference in ages between this year and 2 years ago.