5.2 A runner became ill during the race and was taken to the doctor. The doctor recommended that he take [tex]$11.5 \, mg/kg$[/tex] of an antibiotic per day. The antibiotic is available as a 150 mg capsule.
[Adapted from www.medsalinewstext.com]

5.2.1 If the runner has a BMI of [tex]$28.6 \, kg/m^2$[/tex] and is [tex]1.65 \, m[/tex] tall, show using calculations that [number of] capsules will be the correct dosage for the runner per day.

You may use the formula:
[tex]
BMI = \frac{\text{Mass in kg}}{(\text{height in m})^2}
[/tex]



Answer :

To determine the correct dosage for the runner, we will follow a step-by-step approach based on the information provided:

1. Calculate the Mass of the Runner:
We know the formula for Body Mass Index (BMI):
[tex]\[ \text{BMI} = \frac{\text{Mass in kg}}{(\text{Height in m})^2} \][/tex]
Rearrange the formula to solve for the Mass:
[tex]\[ \text{Mass in kg} = \text{BMI} \times (\text{Height in m})^2 \][/tex]
Given:
[tex]\[ \text{BMI} = 28.6 \, \text{kg/m}^2 \][/tex]
[tex]\[ \text{Height} = 1.65 \, \text{m} \][/tex]
Plug in the values:
[tex]\[ \text{Mass in kg} = 28.6 \times (1.65)^2 \][/tex]
[tex]\[ \text{Mass in kg} = 28.6 \times 2.7225 \][/tex]
[tex]\[ \text{Mass in kg} = 77.8635 \, \text{kg} \][/tex]

2. Calculate the Total Daily Dosage:
The recommended antibiotic dosage is [tex]\(11.5 \, \text{mg per kg}\)[/tex].
[tex]\[ \text{Total daily dosage} = \text{Mass in kg} \times \text{Dosage per kg} \][/tex]
[tex]\[ \text{Total daily dosage} = 77.8635 \, \text{kg} \times 11.5 \, \text{mg/kg} \][/tex]
[tex]\[ \text{Total daily dosage} = 895.43025 \, \text{mg} \][/tex]

3. Determine the Number of Capsules Needed:
Each capsule contains 150 mg of the antibiotic.
[tex]\[ \text{Number of capsules} = \frac{\text{Total daily dosage}}{\text{Dosage per capsule}} \][/tex]
[tex]\[ \text{Number of capsules} = \frac{895.43025}{150} \][/tex]
[tex]\[ \text{Number of capsules} \approx 5.9695 \][/tex]
Since the runner cannot take a fraction of a capsule, we round up to the nearest whole number:
[tex]\[ \text{Number of capsules} = 6 \][/tex]

Therefore, the correct dosage for the runner is 6 capsules per day.