Answer: 189 mg.
Step-by-step explanation:
Let x be the weight of the body( in pounds) and y be the amount of medicine( in mg).
Given: A certain medicine is given in an amount proportional to patient’s body weight.
i.e. [tex]\dfrac{x_1}{y_1}=\dfrac{x_2}{y_2}[/tex]
Let [tex]x_1=116\ \ \ ,\ y_1=126[/tex] , [tex]x_2=174[/tex]
then,
[tex]\dfrac{116}{126}=\dfrac{174}{y_2}[/tex]
[tex]\Rightarrow\ y_2=\dfrac{174\times126}{116}\\\\\Rightarrow\ y_2=189[/tex]
Hence, he amount of medicine required by patient weighing 174 pounds = 189 mg.