(a)

Marks	Class boundary	Freq	Cum freq
0 - 9	0 - 9.5	4	4
10 - 19	9.5 - 19.5	5	9
20 - 29	19.5 - 29.5	6	15
30 - 39	29.5 - 39.5	12	27
40 - 49	39.5 - 49.5	8	35
50 - 59	49.5 - 59.5	5	40

(b) Mode = 35.5
(c) Median = \(L_{1} + \frac{(\frac{N}{2} - \sum f_{p}) \times c}{f_{m}}\)
where \(L_{1}\) = lower class boundary of median class = 29.5
\(N = \sum f = 40\) ; \(\sum f_{p}\) = cumulative frequency before median class = 15.
\(f_{m}\) = frequency of median class = 12, c = class interval = 10.
Median = \(29.5 + \frac{(\frac{40}{2} - 15) \times 10}{12}\)
= \(29.5 + \frac{(20 - 15) \times 10}{12}\)
= \(29.5 + 4.17 = 33.67\)