A recent study found that 37% of incoming students to institutions of higher education were not prepared for the workload and demands of post-secondary education. 9. How large a sample is needed to estimate the true proportion within 2 percentage points with 98% confidence? 1 - 0. 37 = 0. 63 1 - 98./ . = 0.02 Error: 0. 02 10. How large a sample is needed if you had no prior knowledge of the proportion found in this study