The round off errors when measuring the distance that a long jumper has jumped is uniformly distributed between $0$ and $6mm.$ Round values to $4$ decimal places when possible.

a$.$ The mean of this distribution is

b$.$ The standard deviation is

c$.$ The probability that the round off error for a jumper's distance is exactly $1\mathrm{.}8$ is $P(x=1\mathrm{.}8)=$

d$.$ The probability that the round off error for the distance that a long jumper has jumped is between $0$ and $6mm$ is $P(x>4\mathrm{.}8)=P(x>2\mathrm{.}9|x>0\mathrm{.}8)=$