To study the physical fitness of a sample of 28 people, the data below was collected representing the  number of sit-ups that a person could do in one minute.

     10    12     12    15    15     15    18
     20    22     25    25     26    29     30
     32    33     40    40     40     45    46
     47    48     48    50     52     53    56

Determine the lower and upper fences. Are there any outliers according to this criterion