Question

Consider two people being randomly selected. (For simplicity, ignore leap years.)

Answer 1

Answer:

$(a) = \frac{144}{133225} \\\\(b) = \frac{1}{365}$

Step-by-step explanation:

Part (a) the probability that two people have a birthday on the 9th of any month.

Neglecting leap year, there are 365 days in a year.

There are 12 possible 9th in months that make a year calendar.

If two people have birthday on 9th; P(1st person) and P(2nd person).

$=\frac{12}{365} X\frac{12}{365} = \frac{144}{133225}$

Part (b) the probability that two people have a birthday on the same day of the same month

P(2 people selected have birthday on the same day of same month) + P(2 people selected not having birthday on  same day of same month) = 1

P(2 people selected not having birthday on  same day of same month):

$= \frac{365}{365} X \frac{364}{365} =\frac{364}{365}$

P(2 people selected have birthday on the same day of same month) $= 1-\frac{364}{365} \\\\= \frac{1}{365}$