Upper bound or limit of the confidence interval

The superintendent of a unified school district of a small town wants to make sure that no more than 5% of the students skip more than 10 days of school in a year. A random sampleof 145 students from a population of 800 showed that 12 students skipped more than 10 days of school last year. What is the upper bound or limit of the 95% confidence intervalfor the proportion of students who skipped more than 10 days of school last year
A) .1978
B) .1168
C) .1231
D) .1268

Upper bound will be given as
Sample Proportion (p) + 1.645*Sqrt(p*(1-p)/n)
= 12/145 + …

This solution is comprised of a detailed explanation for confidence interval for proportion using hand calculation to find out the correct answer. In this solution, step-by-step explanation of this complicated topic provides students with a clear perspective of 95% confidence interval for proportion with the help of calculations. Formulas are added in word file for better understanding and interpretation is given at the end of question.