Given :
Mass of caffeine at dangerous level , m = 3 g .
Coffee contains , 21.5 mg/oz OF caffeine .
Mass of cup , 8 oz/cup .
To Find :
Number of cups till dangerous level .
Solution :
Caffeine in a cup of coffee is given by :
[tex]C=(21.5\ mg/oz)\times (8\ oz/cup)\\\\C=172\ mg/cup\\\\C=0.172\ g/cup[/tex]
Now , number of cups at the dangerous level is given by :
[tex]n=\dfrac{3\ g}{0.172\ g/cup}\\\\n=17.44\ cups[/tex]
Now , number of cups should be integer .
Therefore , 18 cups of coffee per day is dangerous .
