Posted by **GT** on Friday, July 5, 2013 at 6:35am.

John has a box that contains one red ball and one blue ball. Every minute he reaches into the box and randomly takes out a ball from it (without looking). No matter which ball he took out, he puts it back together with another ball of the same color. Thus, after n minutes, the box contains a total of n+2 balls.

The probability that after 2 hours, the box contains exactly 77 blue balls, can be written as a/b, where a and b are coprime positive integers. Find a+b.

## Answer This Question

## Related Questions

- Math - John has a box that contains one red ball and one blue ball. Every minute...
- maths - one bag contains 1 red ball,1 yellow ball, 1green ball and 1 blue ball ...
- Math - A box contains 20 red balls and 40 green balls . Four balls are randomly ...
- math - A box A contains 9 red balls and 1 white ball. A box B contain 8 red ...
- Conditional Probability - A box contains 1 green ball, 2 blue balls, and 3 red ...
- Statistics - Box A contains 4 red and 6 blue balls. Box B contains 5 red and 10...
- statistics - Box A contains 4 red and 6 blue balls. Box B contains 5 red and 10 ...
- statistics - Box A contains 4 red and 6 blue balls. Box B contains 5 red and 10 ...
- STATISTICS - There are 10 colored balls in a box ( 5 red, 3 blue, 2 green ). ...
- STATISTICS - There are 10 colored balls in a box ( 5 red, 3 blue, 2 green ). ...

More Related Questions