Read the given data and answer the question that follows. $$2,5,15,25,20,12,8,7,6,16,21,17,30,32,23,40,51,15,2,9,57,19,25$$
If the given data is grouped in the classes $0–5$, $5–10$, $10–15$, and so on, then what will be the frequency of the class $20–25$?

In continuous grouping intervals like $20-25$, the lower limit ($20$) is included in the class while the upper limit ($25$) is excluded (it is instead counted in the next class $25-30$). Let's look through the dataset for values that fall in the range $[20,25)$ (i.e., $\ge 20$ and $<25$):$25$ (goes to next class)$20$ (included)$21$ (included)$23$ (included)$25$ (goes to next class)The numbers matching this condition are: $20,21,23$.Thus, there are exactly $3$ items in this frequency class.