The March 14, 2009, Boston Globe article Bargains on the Menuand a Side of Jitters reported concerns

The March 14, 2009, Boston Globe article €œBargains on the Menu€”and a Side of Jitters€ reported concerns that Restaurant Week would not be well attended due to the economy. Local restaurants were coming up with special promotions to draw past and new customers. Keeping this in mind, a waitress wondered if the €œreduced€ prices would also €œreduce€ tip percentages€” especially on the lower-cost promotions and midweek shifts. To test her hypotheses, she collected the following data:

a. At the 0.05 level of significance, do the data provide sufficient reason to support that the day of the week had an effect on the percent tip received?
b. At the 0.05 level of significance, do the data provide sufficient reason to support that the amount of the bill had an effect on the percent tip received?

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Tuesday 21 19 15 Percent hp Thursday 15 17 18 14 Amount of Bill Saturda 12 18 13 10 16 $30-$59 18 14 16 $60-$89 20 14 15 24 21 19 16 15 25 24 30