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Clark’s formula, given below, is used to determine the dosage of medicine for children.
`text(Dosage) = (text(weight in kg × adult dosage))/70`
For a particular medicine, the adult dosage is 325 mg and the correct dosage for a specific child is 90 mg.
How much does the child weigh, to the nearest kg? (2 marks)
`19\ text(kg)`
`90 = (text(weight) xx 325)/70`
| `:.\ text(weight)` | `= (70 xx 90)/325` |
| `= 19.38…` | |
| `= 19\ text(kg (nearest kg))` |
Fried's formula is used to calculate the medicine dosages for children aged 1-2 years.
`text(Child dosage) = {text{Age(in months)}\ xx\ text(adult dosage)}/150`
Ben is 1.5 years old and receives a daily dosage of 450 mg of a medicine.
According to Fried's formula, what would the appropriate adult daily dosage of the medicine be? (2 marks)
`3750\ text(mg)`
`text(Substituting into the formula:)`
| `450` | `= (18 xx text{adult dosage})/150` |
| `:.\ text(Adult dosage)` | `= (450 xx 150)/18` |
| `= 3750\ text(mg)` |
Young’s formula, shown below, is used to calculate the dosage of medication for children aged 1−12 years based on the adult dosage.
`D = (yA)/(y + 12)`
| where `D` | = dosage for children aged 1−12 years |
| `y` | = age of child (in years) |
| `A` | = Adult dosage |
A child’s dosage is calculated to be 20 mg, based on an adult dosage of 40 mg.
How old is the child in years?
A. `6`
B. `8`
C. `10`
D. `12`
`text(D)`
| `D` | `= (yA)/(y + 12)` |
| `20` | `= (40y)/(y + 12)` |
| `20(y + 12)` | `= 40y` |
| `20y + 240` | `= 40y` |
| `20y` | `= 240` |
| `y` | `= 12` |
`=>\ text(D)`
Clark’s formula is used to determine the dosage of medicine for children.
`text(Dosage) = text(weight in kg × adult dosage)/70`
The adult daily dosage of a medicine contains 3150 mg of a particular drug.
A child who weighs 35 kg is to be given tablets each containing 525 mg of this drug.
How many tablets should this child be given daily? (2 marks)
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`3`
| `text(Dosage)` | `= (35 xx 3150)/70` |
| `= 1575\ text(mg)` |
`text(# Tablets per day)`
`= text(Dosage)/text(mg per tablet)`
`= 1575/525`
`= 3`
`:.\ text(The child should be given 3 tablets per day.)`
The formula `D = (2A)/15` is used to calculate the dosage of Hackalot cough medicine to be given to a child.
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The correct dosage of Hackalot cough medicine for Sam is 4 mL.
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| i. | `D` | `= (2A)/15` |
| `= (2 × 9)/15` | ||
| `=1.2\ text(mL)` |
`:.\ text(George should be given a dosage of 1.2 mL)`
ii. `text(Find)\ A\ text(when)\ D = text(4 mL)`
| `4` | `= (2 × A)/15` |
| `2A` | `= 60` |
| `A` | `= 30` |
`:.\ text(Sam is 30 months old and is 21 months)`
`text(older than George.)`
Young’s formula below is used to calculate the required dosages of medicine for children aged 1–12 years.
`text(Dosage) = (text(age of child)\ text{(in years)} xx text(adult dosage))/(text(age of child)\ text{(in years)} + 12)`
How much of the medicine should be given to an 18-month-old child in a 24-hour period if each adult dosage is 45 mL? The medicine is to be taken every 6 hours by both adults and children.
`B`
| `text(Dosage)` | `= (1.5 xx 45)/(1.5 + 12)` |
| `= 5\ text(mL)` |
`text(S)text(ince 1 dosage every 6 hrs)`
`text(In 24 hours,)`
`text(Medicine given) = 4 xx 5 = 20\ text(mL)`
`=> B`