4. The president of a university claims that the mean time spent partying by all students at this university

is not more than 7 hours per week. A random sample of 40 students taken from this university showed

that they spent an average of 9.50 hours partying the previous week with a standard deviation of 2.3

hours. Test at a 2.5% significance level whether the president's claim is true. Explain your conclusion

in words. (5)