NECO 2023 · Paper 1 · Q46

Using the same table, what is the modal score?

Scores	41–50	51–60	61–70	71–80	81–90	91–100
Frequency	8	12	14	16	8	2

Worked solution (try it first)

The modal class is 71–80, with the highest frequency, 16.
Its lower boundary is 70.5 and its width is $c = 10$ .
$D_1 = 16 - 14 = 2$ (the step up from the class before) and $D_2 = 16 - 8 = 8$ (the step down to the class after).
Mode $= 70.5 + \dfrac{2}{2 + 8} \times 10$ , which is $70.5 + 2 = 72.5$ , option C.