There are 10 people in the group. They open a birthday party on the last day of each month if there were birthdays in the group during that month. How many parties are there on average during a year?...

There are 10 people in the group. They open a birthday party on the last day of each month if there were birthdays in the group during that month. How many parties are there on average during a year? Hint: use indicator random variables.

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