according to the experience of a bank staff,there are 2 old paper money IN EACH MONEY PACKET.if the number of old papers money,in each money packet,follow poisson distribution,
- a)what is the probability of that ,there is'nt any old paper money in two money packets?
- b)what is the probability of that ,there are more than 5 old papers money in two money packets?
i'll tried for a:
for (a),i think : 1-((e^-2)(2^x))/x!
a) Obviously the probability there's no old money in 1 money packet is $p_s=e^{-2}$. Since you have two and these events are independent, the probability there's none in 2 is [can you handle from here?]
b) The probability that there are moer than 5 old money banknotes is $1$-probability there are 4 or less. Can you handle from here?