A sample of children age 2-5 years is chosen at random from an outpatient clinic. The number of urinary tract infections (UTIs) over a 1-year period is given in the figure below. What was the average number of UTI episodes over 1 year for a child in this sample?

Question

A sample of children age 2-5 years is chosen at random from an outpatient clinic.  The number of urinary tract infections (UTIs) over a 1-year period is given in the figure below.  What was the average number of UTI episodes over 1 year for a child in this sample?

Quizplus · Accepted Answer

Eductional Objective: This bar graph illustrates the frequency of urinary tract infection (UTI) episodes in the sample. According to the figure, 50 children had 0 UTIs, 30 children had 1 UTI, 10 had 2 UTIs, and 10 had 3 UTIs.
In general, the average (or mean) of a dataset is the sum of the values divided by the total number of values. In this example, the average number of UTI episodes per child is the sum (ie, total number) of UTIs divided by the total sample size (ie, total number of children). The total sample size is: 50 + 30 + 10 + 10 = 100 children. The total number of UTIs is: (0 × 50) + (1 × 30) + (2 × 10) + (3 × 10) = 0 + 30 + 20 + 30 = 80 UTIs. The average is obtained by dividing the total number of UTIs (80) by the total sample size (100). Therefore, the average number of UTI episodes per year = 80/100 = 0.8 UTIs for a child in this sample.
In conclusion, children age 2-5 years in this clinic experienced between 0 and 1 UTI over 1 year on average.

A Sample of Children Age 2-5 Years Is Chosen at Random