The following class intervals for a frequency distribution were developed to provide information regarding the starting salaries for students graduating from a particular school:
Salary Number of Graduates
($1,000s)
28-under 31 -
31-under 35 -
34-under 37 -
39-under 40 -
Before data was collected, someone questioned the validity of this arrangement. Which of the following represents a problem with this set of intervals?