A cereal company is putting 1 of 4 prizes in each box of cereal. The prizes are evenly distributed so the
probability of winning any given prize is always 1/4.
Lily wonders how many boxes she should expect to buy to get all 4 prizes. She carried out 20 trials of a
simulation and her results are shown below. Each dot represents how many boxes it took to get all 4 prizes in
that trial.
4
5
6
7
8
9
10 11 12 13 14 15
# of boxes purchased
Use her results to estimate the probability that it takes fewer than 7 boxes to get all 4 prizes.
Give your answer as either a fraction or a decimal.
P(fewer than 7 boxes) -