Question

 An economist conducted a study to identify the percentage of family income allocated to the purchase of groceries. She surveyed a random sample of 50 families and compiled the following numeric frequency distribution:

 Percent of income

  Number of families

 10 – under 20% 6

 20 – under 30%

  14

 30 – under 40%

  16

 40 – under 50%

 10

 50 – under 60%

  4

 2.2.1 Compute and interpret the (approximate) mean percentage of family income allocated to grocery purchase. (Hint: Use the weighted average formula with the midpoint of each interval as xi.