When choosing an interval to use for a frequency table, the low value and the high value of the dat is considered so that the interval refrects a true data size for all the intervals.
Given that a data set has values ranging from a low of 10 to a high of 52. Using the class limits of 10-19, 20-29, 30-39, 40-49 for a frequency table will make the last interval not to refrect the true size of the other intervals. i.e. the last interval will be 50 - 52 which has a size of 3, different from the size of 10 the other intervals have.