Question

Go to a local library; collect a sample of books consisting of the ages of book (based on copyright dates). Plan and describe the sampling procedure, then use the results to construct a confidence interval estimate of the mean age of all books in the library. Please, post and share your results with the class.

Answer 1

I use the method of stratified random sampling to collect the sample of books. I randomly select 4 types of books namely friction, cooking, historical, and love stories. My strata is the type of book. From each of these book type (strata), I randomly select 10 books. I expect no bianess in the data, as my sample is a good representative of the population.

I take the level of significance Alpha as 5%. this indicates I am 95% confident about my results. The data obtained from the library regarding the age of book is given below.

Data Descriptive Statistics is 1 Avenage 13 Mean 8.25 4.29 Standard deviation 13 Sd=5 vay 40.00 COUNT h = 13 8 alpha= 0.05 13 6 To lo The confidence intenval is given by Z (0/2) => Z (0.05/2) =) 1960 C-I = mean +(-2) (1.1-1] * [ S ] 15 2 15 40 11 lowers 8-25-1-96*[4289223 ] = 6.92 uppen - 8.25 + 1.968 4.289223 22 2] x[ 9 29.58 12 J40 9 6 1 15 6 10 9 This indicates that I am 95 J. Confidence Interval that estimated population mean age of books lies in the interval [ 6.92, 9.58] years 11 2 2 2 7 4 11 3 10 18