NAPLEX (North American Pharmacist Licensure Examination) Practice Exam

The formula for calculating specific gravity is the weight of a substance divided by the weight of an equal volume of water. This is because specific gravity is a ratio of the density of a substance to the density of water, and density is calculated using weight and volume. Option A would not result in an accurate specific gravity calculation as it does not take into account the weight of the substance. Option C is also incorrect as it reverses the order of the weight values, which would result in an incorrect ratio. Option D involves using densities, which are not the same as weight, making this formula incorrect for calculating specific gravity.