In a sample of 100 people who have had strokes, the average cholesterol level was 250 with a standard deviation of 40.

In a sample of 100 people who have had strokes, the average cholesterol level was 250 with a standard deviation of 40. In order to test the hypothesis (at the 5% level of significance) that the average cholesterol level of people who have had strokes was at least 240, what is the null and alternative hypotheses?