In $1914,$ Fletcher $($Phys$.$ Rev. $4,440)$ published a paper describing his experimental

verification of diffusion coefficients. His measurements were based on

the distribution of settling times for a particle settling over a fixed vertical distance.

Fletcher was able to make $6000$ replications on a single particle by

raising the particle back up to the starting point with an electric field. If his

particle was $0\mathrm{.}36\backslash$mu $\backslash$eta in diameter and the settling distance was $0\mathrm{.}74$ mm$,$ what

were the theoretical mean and standard deviation of the settling times? Assume

that there was no experimental error and that the standard deviation was

much less than the mean. pp $=1000$ kg$/$m$3$

$[1\mathrm{.}0$ g$/$cm$3].$ Approximately how

long did it take to conduct this experiment? Assume that $25$ s was required

to reposition the particle after each measurement.