# Thread: Discrete Probiality problem

1. ## Discrete Probiality problem

Hi

Can someone help me on how to answer the following question:

In testing a certain kind of truck tyre over rugged terrain, it is found that 25% of trucks suffer tyre blowout.

What is the probability that at least two trucks will complete the course without tyre blowout before the next truck suffers from tyre blowout?

I think this is using Poisson distribution but not sure.
Such as Pr( without blowout > 2) + Pr( with blowout > 2)

P.S

2. ## Re: Discrete Probiality problem

i dont think you need a poisson distribution here.

if two trucks pass before the next one fails, then you must have the next two trucks passing. These are independant (i assume) with probability 75% each.

can you finish from there?

3. ## Re: Discrete Probiality problem

so what type of distribution is this? if any?
sorry i still cannot seem to do it

4. ## Re: Discrete Probiality problem

The distribution of the number of blowouts from the next two trucks is binomial. You are interested in the probability that the number of blowouts from the next two trucks is 0.

5. ## Re: Discrete Probiality problem

What was the answer you obtained?

where X is the number of blowouts suffered
so symbolically this is defined as: 1- Pr(X > 2)