JAMB 1993 · UME · Q45

Estimate the mode of the frequency distribution below.

Weight (g)	0–10	10–20	20–30	30–40	40–50
No. of coconuts	10	27	19	6	2

Worked solution (try it first)

The modal class has the highest frequency: 10–20 g, with 27 coconuts.
Differences from the neighbouring classes: $\Delta_1 = 27 - 10 = 17$ and $\Delta_2 = 27 - 19 = 8$ .
Mode $= L + \frac{\Delta_1}{\Delta_1 + \Delta_2} \times c$
$= 10 + \frac{17}{25} \times 10$ , which is $10 + 6.8$ .
So the mode is about 16.8 g, option C.