Many companies are experimenting with “flex-time,” allowing employees to choose their schedules with broad limits set by management. Among other things, flex-time is supposed to reduce absenteeism.
One firm knows that in the past few years, employees have averaged 6.3 days off from work (apart from vacations). This year the firm introduces flex-time. Management chooses a simple random sample of 100 employees to follow in detail, and at the end of the year, these employees average 5.5 days off from work, and the standard deviation is 2.9 days.
What is the null hypothesis?
(A) The average days off work for the employees in the sample is different from the average days off work for the employees overall.
(B) The average days off work for the employees in the sample is the same as the average days off work for the employees overall.
I think it would be B but I am not sure. I do not really understand null hypothesis. Would it be the contrary of what he is trying to prove?