How many milliliters of a 0.40%(w/v) solution of nalorphine must be injected to obtain a dose of 1.5 mg?

The number  of Ml  of  a  0.40 %w/v solution  of   ,nalorphine  that must  be injected  to  obtain  a  dose  of 1.5 mg is  calculated as  below

since M/v%   is  mass  of solute  in  grams per 100  ml

convert Mg to  g
1 g = 1000 mg  what  about  1.5 mg =?  grams
=   1.5 /1000 = 0.0015 grams

volume is therefore =  100 (  mass/ M/v%)

= 100  x(  0.0015/ 0.4) =  0.375  ML