(a)

Scores (x)	Frequency (f)	\(fx\)
1	2	2
2	5	10
3	13	39
4	11	44
5	9	45
6	10	60
	\(\sum f = 50\)	\(\sum fx = 200\)

\(Mean (\bar{x}) = \frac{\sum fx}{\sum f} = \frac{200}{50} = 4\)

\(d = x - 4\)	\(|d|\)	f	\(f|d|\)
-3	3	2	6
-2	2	5	10
-1	1	13	13
0	0	11	0
1	1	9	9
2	2	10	20
			\(\sum f|d| = 69\)

Hence, Mean Deviation = \(\frac{\sum f|d|}{\sum f} = \frac{69}{50} \)
= \(1.38\)
(b) Let E denote the event of getting a score of at least 4.
\(n(E) = 11 + 9 + 10 = 30\)
\(p(E) = \frac{n(E)}{n(S)} = \frac{30}{50}\)
= \(0.6\)