35 ml of a sample are obtained from a crime scene where the ratio of blood to water is 7:3. how much of the sample was blood?
let the amount of blood be 7x
the amount of water be 3x
7x + 3x = 35
x = 3.5
then 7x = 24.5
24.5 ml was blood, and 10.5 was water
check:
24.5 : 10.5
= 49 : 21
= 7 : 3