Purchase Solution

# Probability: Birthdays on the Same Day

Not what you're looking for?

Determine the number of people needed to ensure that the probability at least two of them have the same day of the year as their birthday is at least 70 percent, at least 80 percent, at 90 percent, 95 percent, at least 98 percent, and at least 99 percent.

##### Solution Summary

The probablities of people having ths same birthday are investigated using permutations.

##### Solution Preview

Let's say the number of people needed to meet the probability is N. We will also assume that a year has 365 days (no leap years!).
The easiest way to think about it is to find the probability that NO two people have the same birthday. Then the probability that AT LEAST two people have the same birthday will be 1- (probability that NO two people have the same birthday).

We fix 'N' and determine the probability that no two people, in a room of N people, have the same birthday. Say that the people are
P(1),P(2),...,P(N). Now person P(1) may have any of the 365 days of the year for his birthday without contradicting the condition that no two people in the room will have the same birthday i.e. the ...

##### Free BrainMass Quizzes

Each question is a choice-summary multiple choice question that will present you with a linear equation and then make 4 statements about that equation. You must determine which of the 4 statements are true (if any) in regards to the equation.

This quiz test you on how well you are familiar with solving quadratic inequalities.

##### Probability Quiz

Some questions on probability

##### Geometry - Real Life Application Problems

Understanding of how geometry applies to in real-world contexts

##### Multiplying Complex Numbers

This is a short quiz to check your understanding of multiplication of complex numbers in rectangular form.