The average amount of money a person spends on lottery tickets each month is $4.$ By looking at the data$$ set, a Poisson discrete distribution is assumed for this variable. Calculate each of the following.

a$.$ The probability of buying no lottery ticket.

b$.$ The probability of buying $2$ lottery tickets.

c$.$ The probability of buying $3$ lottery tickets.

d$.$ The probability of buying fewer than or equal $3$ tickets.