1. The reaction times of 150 randomly selected drivers were foun4 to have a mean of .83 sec and standard deviation of .20 sec. Find a 95 confidence interval for the mean reaction time of the whole population of drivers.
2. From a very large class in statistics, the following 40 marks were randomly selected:
71 74 65 72 64 42 62 62 58 82
49 83 58 65 68 60 76 86 74 53
78 64 55 87 56 50 71 58 57 75
58 86 64 56 45 73 54 86 70 73 Construct a 95% confidence interval for the average mark of the whole class.