Using it's concept, the probabilities are given as follows:
a) C. 7/20.
b) D. 15/22.
<h3>What is a probability?</h3>
A probability is given by the <u>number of desired outcomes divided by the number of total outcomes</u>.
For item a, we have that there are 60 students with no curfew, and of those, 21 have no chores, hence the probability is given by:
p = 21/60 = 7/20
Which means that option C is correct.
For item b, we have that there are 66 students with no shores, and of those, 45 have a curfew, hence the probability is given by:
p = 45/66 = 15/22
Which means that option D is correct.
More can be learned about probabilities at brainly.com/question/14398287
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Maybe if you show the graph picture it would help
