Question

People were polled on how many books they read the previous year. Initial survey results indicate that sequals17.7 books. Complete parts ​(a) through ​(d) below. LOADING... Click the icon to view a partial table of critical values. ​(a) How many subjects are needed to estimate the mean number of books read the previous year within six books with 90​% ​confidence? This 90 % confidence level requires 0.05 subjects. ​(Round

Answer 1

Solution :

Given that,

Population standard deviation = s = 17.7

Margin of error = E = 6

At 90% confidence level the z is ,

= 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

Z_/2 = Z _0.05 = 1.645

sample size = n = (Z_/2* s / E) ²

n = (1.645 * 17.7 / 6)²

n = 23.54

n = 24

This 90 % confidence level requires 24 subjects