- #1

- 374

- 7

## Homework Statement

The minimum number of throws of a pair of dice so that the probability of getting the sum of the digits on the dice equal to 7 on atleast one throw is greater than 0.95, is n. Find n.

## Homework Equations

## The Attempt at a Solution

There are 6 possible ways of getting a sum of 7.

So, P(7) = 6/36 = 1/6 and P(not 7) = 5/6

For minimum number of throws, on the last throw the sum should be 7.

So,

(5/6)

^{n-1}(1/6) > 0.95

(5/6)

^{n-1}> 5.7

Solving for n gives an incorrect answer.