### Home > CCA2 > Chapter 11 > Lesson 11.2.3 > Problem11-64

11-64.

A copy machine company advertises that its copiers will make at least $25{,}000$ copies before requiring maintenance. A consumer research group tested the claim by collecting data from users of the particular copy machine in $30$ different regions of the country. The means for each of the $30$ regions are listed in the table below.

 $24928$ $24574$ $24652$ $24758$ $24691$ $24893$ $25024$ $24767$ $24791$ $24609$ $25249$ $24914$ 24895 $24656$ $24883$ $24551$ $24928$ $25025$ $24798$ $25041$ $24782$ $25020$ $24618$ $24904$ $24764$ $24705$ $24889$ $24656$ $24600$ $24735$ checksum $744300$

Find the upper and lower $5\%$ bounds of the sample-to-sample variability and predict the number of copies that can be made before a machine requires maintenance. Do you think the consumer research group will support the company’s claim?

Read the Math Notes box in Lesson 11.2.2.