In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[Q]: Catholic systems comprise _ of the twenty largest healthcare systems in the country.
[A]: ten

[Q]: Monsoons coming every three to _ years can add almost a foot of water to the mountain's surface.
[A]: seven

[Q]: Hoary marmots are active about _ and a half months each year.
[A]:
four