# What is the probability that there are even more accidents on Friday then on Thursday given distribution independent of other days?

Every day, the number of traffic accidents has a distribution (probability mass function)

x    0    1    2    >2
P(x) 0.6  0.2  0.2  0


independently of other days. What is the probability that there are even more accidents on Friday then on Thursday?

This is a practice exam problem so the exact answer isn't as helpful as the proper solution.

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There is nice symmetry to exploit. Let $p$ be the probability of "more on Friday." Then $p$ is also the probability of more on Thursday. And $2p+e=1$, where $e$ is the probability the number of accidents is the same.
Once we know $e$, we will know $p$.
The probability the number of accidents is the same is the probability they are both $0$, plus the probability they are both $1$, plus the probability they are both $2$.
The probability they are both $0$ is $(0.6)^2$. Continue.