9. The measure of two angles are (16.5 +1.5n)°and (12 + 2n)°. What is
the value of n if these angles are congruent?

(16.5 + 1.5n)° = (12 + 2n)° [given]

=> 16.5 – 12 = 2n – 1.5n

=> 4.5 = 0.5n

=> n = 4.5/0.5

=> n = 9

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.