Question

Ignore, for simplicity, the possibility of being born on February 29th. Assume that a person is just as likely to be born on any one date as on any other date, excluding February 29th, of course.

Suppose 253 people are picked at random. (We use 253 since e” = 1/2 almost exactly. Use 1/2 in your computations.)

c. What is the expected number of different birthdays of the group?

d. The expected number of days which are each the birthday of at least two of the people?

Answer 1

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Let x-no. of days brihdys -) E (x)Sum E(li) Sum Sum P(day i has tleast 2 brth days Sum (i- 8day 4 has 0 had (1-(34 1sts) 253 25326421 1 262 345 756 5 5.947 18