RRB ALP CBT I 11 Feb 2026 Shift 1 Paper

Concept:The mode formula for grouped data is used. The given mode value helps identify the modal class first.Explanation:The mode is given as $37.5$, which falls within the class interval $30-40$. Hence, the modal class is $30-40$.For this modal class: lower limit $l = 30$, frequency of modal class $f_1 = 7$, frequency of preceding class $f_0 = 4$, frequency of succeeding class $f_2 = p$, and class width $h = 10$.The mode formula is:$$Mode = l + \left[\frac{f_1 - f_0}{2f_1 - f_0 - f_2}\right] \times h$$Substituting the known values:$$37.5 = 30 + \left[\frac{7 - 4}{2(7) - 4 - p}\right] \times 10$$$$37.5 - 30 = \left[\frac{3}{14 - 4 - p}\right] \times 10$$$$7.5 = \left[\frac{3}{10 - p}\right] \times 10$$$$7.5 = \frac{30}{10 - p}$$$$10 - p = \frac{30}{7.5} = 4$$$$p = 10 - 4 = 6$$Answer:The missing frequency is $p = 6$. Hence, option C is the correct answer.