- A bag contains 19 red beads and 1 blue bead only.
Linda selects a bead at random from the bag. She notes its colour and replaces the bead in the bag. She then selects a second bead at random from the bag and notes its colour.
Find the probability that
- both beads selected are blue,
- exactly one bead selected is red.
In another bag there are 9 beads, 4 of which are green and the rest are yellow.
Linda selects 3 beads from this bag at random without replacement. - Find the probability that 2 of these beads are yellow and 1 is green.
Linda replaces the 3 beads and then selects another 4 at random without replacement.
- Find the probability that at least 1 of the beads is green.