Two-step experiments

Steps

1. Table when both steps have the same outcomes (two dice): fill a 6 × 6 grid and count.
2. Tree diagram otherwise:
   1. One set of branches per step. Write the probability on each branch.
   2. Multiply along a path.
   3. Add the paths that give the event.
3. Without replacement: on the second step, the total goes down by 1, and so does the count of whatever was taken.

For the whole topic, read Probability: key points, common mistakes and how the DSE tests it.

Other methods in this topic