1. A box contains 4 black and 2 white beads.
   A bead is taken at random, its colour noted and replaced, then a second is taken.
   The tree diagram is partly complete.
   Find the probability marked $?$ (the second pick being white after a black).
2. The probability Priya revises on a given evening is $\dfrac{3}{5}$.
   If she revises, the probability she passes the weekly quiz is $\dfrac{3}{5}$.
   If she does not revise, the probability she passes is $\dfrac{1}{2}$.
   Complete the tree diagram.
   Use it to find the probability that Priya revises and passes the quiz.
3. A bag contains $n$ orange sweets and 2 lemon sweets.
   Two sweets are taken at random without replacement.
   The probability that both sweets are orange is $\dfrac{15}{28}$.
   Work out the value of $n$.

1. A box contains 4 black and 2 white beads.
   A bead is taken at random, its colour noted and replaced, then a second is taken.
   The tree diagram is partly complete.
   Find the probability marked $?$ (the second pick being white after a black).
2. The probability Priya revises on a given evening is $\dfrac{3}{5}$.
   If she revises, the probability she passes the weekly quiz is $\dfrac{3}{5}$.
   If she does not revise, the probability she passes is $\dfrac{1}{2}$.
   Complete the tree diagram.
   Use it to find the probability that Priya revises and passes the quiz.
3. A bag contains $n$ orange sweets and 2 lemon sweets.
   Two sweets are taken at random without replacement.
   The probability that both sweets are orange is $\dfrac{15}{28}$.
   Work out the value of $n$.

1. A box contains 4 black and 2 white beads.
   A bead is taken at random, its colour noted and replaced, then a second is taken.
   The tree diagram is partly complete.
   Find the probability marked $?$ (the second pick being white after a black).
2. The probability Priya revises on a given evening is $\dfrac{3}{5}$.
   If she revises, the probability she passes the weekly quiz is $\dfrac{3}{5}$.
   If she does not revise, the probability she passes is $\dfrac{1}{2}$.
   Complete the tree diagram.
   Use it to find the probability that Priya revises and passes the quiz.
3. A bag contains $n$ orange sweets and 2 lemon sweets.
   Two sweets are taken at random without replacement.
   The probability that both sweets are orange is $\dfrac{15}{28}$.
   Work out the value of $n$.

1. A box contains 4 black and 2 white beads.
   A bead is taken at random, its colour noted and replaced, then a second is taken.
   The tree diagram is partly complete.
   Find the probability marked $?$ (the second pick being white after a black).
2. The probability Priya revises on a given evening is $\dfrac{3}{5}$.
   If she revises, the probability she passes the weekly quiz is $\dfrac{3}{5}$.
   If she does not revise, the probability she passes is $\dfrac{1}{2}$.
   Complete the tree diagram.
   Use it to find the probability that Priya revises and passes the quiz.
3. A bag contains $n$ orange sweets and 2 lemon sweets.
   Two sweets are taken at random without replacement.
   The probability that both sweets are orange is $\dfrac{15}{28}$.
   Work out the value of $n$.