Questions: The dosage of a certain drug is related to the weight of a child as follows: 10 mg of the drug and an additional 10 mg for each 5 lb or fraction of 5 lb of body weight above 60 lb . Which of the following graphs is the graph of dosages as a function of weight for a child who weighs between 50 and 70 lb ? Choose the correct graph below. A. B. C.

Solution Steps

The dosage of the drug is given as:

• 10 mg for any weight.
• An additional 10 mg for each 5 lb or fraction of 5 lb above 60 lb.

• For 50 lb to 60 lb: The dosage is 10 mg (since the weight is not above 60 lb).
• For 61 lb to 65 lb: The dosage is 10 mg + 10 mg = 20 mg (since the weight is above 60 lb by up to 5 lb).
• For 66 lb to 70 lb: The dosage is 10 mg + 20 mg = 30 mg (since the weight is above 60 lb by up to 10 lb).

• Graph A: Shows a constant dosage of 10 mg for weights 50 to 60 lb, then increases to 20 mg for weights 60 to 65 lb, and 30 mg for weights 65 to 70 lb.
• Graph B: Shows a constant dosage of 10 mg for weights 50 to 60 lb, then increases to 20 mg for weights 60 to 65 lb, and remains constant at 20 mg for weights 65 to 70 lb.
• Graph C: Shows a constant dosage of 10 mg for weights 50 to 60 lb, then increases linearly to 30 mg for weights 60 to 70 lb.

Final Answer