a)
1 in 10 or 10^-1
b)
1 in 1000 or 10^-3 (that is if it is a serial dilution following the
first 1 in 10 dilution.
If you are starting with the pure undiluted sample, it is 1 in 100,
or 10^-2.
Edited by xarqi on April 28 2005 at 6:34am

