subject.... discrete structure

1

.

A chain letter starts when a person sends a letter to five

others. Each person who receives the letter

either sends it

to five other people who have never received it

or does not

send it to anyone. Suppose

that 10,000 people send out

the letter before the chain ends and that no one receives

more than one

letter. How many people receive the letter,

and how many do not send it out?