Question

I conducted a poll and asked 1012 students how many books they read last year. The data indicates x = 12.1 books and s = 16.6 books. Construct a 90% confidence interval for the number of books the students read. Z = 1.645

Answer 1

(11.242 ; 12.958)

Explanation:

The confidence interval is obtained using the relation :

C. I = xbar ± Zcritical * s/√n

Given that ::

xbar = 12.1 ;

Standard deviation, s = 16.6

n = 1012

C. I = 12.1 ± 1.645 * (16.6/√1012)

C.I = 12.1 ± 0.8583881

C. I = 11.242 ; 12.958