Question 2
Use each of the following rules to calculate the amount of medicine a 4-year-old child weighing 17 kg needs if the adult amount is 600 mg.
| a |
Young's rule (using the age of the child) |
| |
 |
Child amount = Adult amount × \(\dfrac{\text{Age of child}}{\text{Age of child}+12}\). |
| b |
Clark's rule (using the weight of a child) |
| |
|
Child amount |
= Adult amount × \(\dfrac{\text{Weight of child (lb)}}{150}\).• |
| |
|
|
= Adult amount × \(\dfrac{\text{Weight of child (kg)}\times2.2}{150}\).• |
Solutions
| a |
Child amount |
= Adult amount × \(\dfrac{\text{Age of child}}{\text{Age of child}+12}\). |
| |
|
= 600 × \(\dfrac{4}{4+12}\) |
| |
|
= 600 × \(\dfrac{4}{16}\) |
| |
|
= 600 × \(\dfrac{1}{4}\) |
| |
|
= 150 mg. |
| b |
Child amount |
= Adult amount × \(\dfrac{\text{Weight of child (kg)}\times2.2}{150}\). |
| |
|
= 600 × \(\dfrac{17\times2.2}{150}\) (Use a calculator.) |
| |
|
= 149.6 mg. |
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