This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
The probability of Koichi accidentally falling into this pit is at about 20%.
What's the likelihood of Koichi being someone who's kind to his friends?
Viet told Koichi that the chances of Tofugu succeeding were 200%.