What is 500 divided by 90? (Don't respond if you dont want alot of notifications)

We just started the introduction into circles and i have no idea how to do this.

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

This is about circle theorems. someone asap : (