Let's go through the problem step by step and ensure all frequencies and relative frequencies are correct.

Data Set:

• 21, 21, 21, 24, 25, 30, 35, 38, 41, 41, 42, 43, 47, 47, 53, 54

Step 1: Frequency Count for Each Class

• Class 20-29: The numbers in this class are 21, 21, 21, 24, 25.

  • Frequency: 5 (already correct)

• Class 30-39: The numbers in this class are 30, 35, 38.

  • Frequency: 3 (the previous entry of 2 is incorrect)

• Class 40-49: The numbers in this class are 41, 41, 42, 43, 47, 47.

  • Frequency: 6 (the previous entry of 7 is incorrect)

• Class 50-59: The numbers in this class are 53, 54.

  • Frequency: 2 (already correct)

Step 2: Total Frequency

Sum of frequencies:
$5 + 3 + 6 + 2 = 16$

Step 3: Calculating Relative Frequencies

To find the relative frequency, divide each class's frequency by the total frequency (16) and round to four decimal places.

• Class 20-29:
  $\text{Rel. Freq} = \frac{5}{16} = 0.3125$ (correct)

• Class 30-39:
  $\text{Rel. Freq} = \frac{3}{16} = 0.1875$ (previous answer of 0.1250 was incorrect)

• Class 40-49:
  $\text{Rel. Freq} = \frac{6}{16} = 0.3750$ (previous answer of 0.4375 was incorrect)

• Class 50-59:
  $\text{Rel. Freq} = \frac{2}{16} = 0.1250$ (correct)

Final Table:

Class	Frequency	Rel. Freq
20-29	5	0.3125
30-39	3	0.1875
40-49	6	0.3750
50-59	2	0.1250

Would you like further details or have any other questions?

Here are 5 related questions to expand your understanding:

1. How do you calculate cumulative frequency?
2. What is the sum of all relative frequencies in this table?
3. What is the mode of the original data set?
4. How would the frequency distribution change if the classes were in intervals of 10?
5. How would you find the median of the data set?

Tip: Relative frequencies are a great way to compare data distributions of different sizes, as they normalize the frequencies into proportions.