Discussion

Answer: C

The modal class is the one with the highest frequency, which is 20-30 (frequency = 15).

We use the formula for the mode of grouped data:

Mode = \(L + \frac{f_m - f_1}{2f_m - f_1 - f_2} \times h\)

• L (lower limit of modal class) = 20
• h (class width) = 10
• f_m (frequency of modal class) = 15
• f₁ (frequency of the class preceding the modal class) = 10
• f₂ (frequency of the class succeeding the modal class) = 12

Mode = \(20 + \frac{15 - 10}{2(15) - 10 - 12} \times 10\)

Mode = \(20 + \frac{5}{30 - 22} \times 10 = 20 + \frac{5}{8} \times 10\)

Mode = \(20 + \frac{50}{8} = 20 + 6.25 = 26.25\).