SAT Probability study notes

SAT probability questions often hide the denominator in a table. The word ‘of’ tells you which group to restrict to. Read the row and column labels first, then count favorable cases inside that group. A conditional percentage uses the same numerator and denominator as a conditional probability.

Worked example

Of the students who completed an assignment, what fraction attended the tutoring session?

The ‘completed’ column contains 30 tutoring students and 18 other students. The denominator is therefore 48, not all 80 students. The requested fraction is 30/48 = 5/8.

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