Question

Some researcher surveyed 300 students if they plan to continue their education, or finish before master program. Of the 300 students surveyed, 120 responded yes - they hope to continue for a graduate degree. Using an 85% confidence level, find a lower and upper level of the confidence interval estimate for the true proportion of students in master program.

Write your answer in percents, round the number to the nearest tenth.

Answer 1

Sample proportion, = 120 / 300 = 0.4

Standarrd error = = = 0.0283

Z score for 85% confidence level is 1.44

Lower limit of confidence interval estimate for the true proportion of students in master program

= 0.4 - 1.44 * 0.0283 = 0.359 = 35.9 %

Upper limit of confidence interval estimate for the true proportion of students in master program

= 0.4 + 1.44 * 0.0283 = 0.441 = 44.1 %