Solution: Assuming that everyone infects X people on average, then:

After the first round, (1+x) people got the flu.

After the second round, [1+x+( 1+x)*x] people got the flu.

Then there is the equation:

1+x+( 1+x)*x=64

X=7 (because (1+x)*( 1+x)=64, and because X >；; 0, so1+x >; 0, so 1+x=8, so x=7)

A: In each round of infection, the average person is infected with 7 people.

So 64*7+64=5 12 (person)

A: At this rate, 565,438+02 people will get the flu after three rounds of infection.