If OC= 12 and BC = 5, then what is the radius?

Fredrick designed an experiment in which he spun a spinner 20 times and recorded the results of each spin

Aclass consists of 55% boys and 45% girls. it is observed that 25% of the class are boys and scored an a on the test, and 35% of the class are girls and scored an a on the test. if a student is chosen at random and is found to be a girl, the probability that the student scored an ais

How do i do this? i don’t understand