Here is a probability scale:
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
There are 3 white counters and 2 black counters in a bag.
I take one of the counters at random.
Put a cross on the probability scale to show the probability
that I have chosen one of the white counters.