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