A postgraduate researcher conducted a study to determine whether preferred teaching methods differ by teacher experience level. A random sample of 240 teachers was asked about their most preferred instructional approach. Results are as follows:

	Teacher's Teaching experience
Teaching Method	1-5 yrs	6-10 yrs	11-15 yrs	Over 15 yrs
Lecture	10	17	18	20
Group Work	14	19	16	13
Discussion	9	15	14	11
Project-Based	7	12	10	5

Required: a) State the null and alternative hypotheses (2 marks) b) Compute a chi-square test for the above data (5 marks) c) Test, at the 1% level of significance, whether there is sufficient evidence to conclude that the preferred teaching method varies by experience level (2 marks)