+0

Both groups seemed equally eager to participate in the tasks, but the urban mice were better at solving the novel ones. They had a 77% success rate compared to the rural mice's 52%.

Could you tell me why 's is used?

+1

It's a possessive: "rural mice's 52%" means "52% (success rate) of the rural mice".

Comments  
Students: Are you brave enough to let our tutors analyse your pronunciation?

And the rural mice all got eaten by the farm cats in under a minute in a follow-up experiment.

Thank you very much.

Insurance occupied 66% of the total budget in comparison with staff training's 35%.

Could you check my example sentence?

Nhật BìnhInsurance occupied 66% of the total budget in comparison with staff training's 35%.
Could you check my example sentence?

In my view, the use here of the possessive "staff training's" is slightly verging on the awkward, but can be accepted. Opinions may vary.

"occupied" may not be the very best choice of verb.

66% and 35% add up to more than 100%!

Students: We have free audio pronunciation exercises.