This short article gives an outline of the origins of Morse code and its inventor and how the frequency of letters is reflected in the code they were given.
In this short problem, can you deduce the likely location of the odd ones out in six sets of random numbers?
Is the age of this very old man statistically believable?
Try constructing frequency tables.
If you are having trouble getting started, you might like to try the similar Stage 4 problem Which list is which?