How much medicine does our elderly sheep need if the medicine contains 20mg drug / ml and sheep need 1mg/kg. Our sheep weighs 70kg.
First work out how many ml of medicine contains 1mg drug
So there are 20mg drug in 1ml of medicine
and if I divide both parts by 20 then I keep the ration in balance
So there are 20/20 mg drug in 1/20ml of medicine
= 1mg drug in 0.05ml of medicine
A sheep needs 1mg of drug per 1kg of weight
From above this is equal to 0.05ml of medicine per 1kg of weight
Our sheep weighs 70kg so we can multiply both parts by 70 to find out how much medicine the sheep needs
70x0.05ml of medicine for 70x1kg weight sheep
= 3.5ml of medicine for a 70kg sheep