Question

People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 95% ​confidence? Initial survey results indicate that sigmaσequals=15.3 books.

Answer 1

Solution :

Given that,

standard deviation = = 15.3

margin of error = E = 1

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z_/2 = Z_0.025 = 1.96

Sample size = n = ((Z_/2 * ) / E)²

= ((1.96 * 15.3) / 1)²

= 899.2

Subjects = 900