Why is the greatest common factor of 2 numbers sometimes 1

The ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?

The ratio of wooden bats to metal bats in the baseball coach’s bag is 2 to 1. if there are 20 wooden bats, how many metal bats are in the bag?

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