Answer
The average speed of my hair is $6.41\times10^{-9}cm/s$
Work Step by Step
My hair grows about 0.10 m in 6 months = 180 days.
$180 days = (180 days)(\frac{24 h}{1 day})(\frac{3600s}{1h})=1.56\times10^{7}s$
$Average$ $speed=\frac{distance}{elapsed time}=\frac{0.10m}{1.56\times10^{7}s}=6.41\times10^{-9}m/s$
