In Dr. Mosley's waiting room, 4 magazines are scattered on the chairs. A patient named Tristan decides he probably has time to skim 3 magazines before his name is called. In how many orders can Tristan pick out 3 of the 4 magazines?

Tristan can pick them out in 6 different ways

Step-by-step explanation: In the waiting room the four magazines all have an equal chance of being picked first and then others would be picked subsequently. If we are to pick magazine A first of all, then the others would be picked as B, C and D, or C, B and D, or D, B and C, and so on.

However, rather than spend so much time counting the different ways we can apply the mathematical method of permutation. Since choosing the first one means we can’t choose it again but others have to be chosen, and all four magazines each has an equal chance of being chosen first, then the number of all possible permutations is given as 4! (four factorial).

The question requires us to chose three out of the four magazines, so we shall apply 3!.

3! = 3 x 2 x 1

3! = 6

Therefore, there are 6 different ways to pick three out of the four magazines

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.