There are 45,578 Year 12 students in Queensland that are completing QCS for the first time. The first sample of 2000 students (randomised) was collected to calculate the average test scores. From this sample the mean score was 71.9 and the standard deviation was 24.2. A 95% confidence interval was calculated which suggested the mean QCS score was between 70.82 and 72.96. What is the number of observations that will bring the lower bound within 0.5 marks of the mean? Write you answer to the nearest whole number.