A veterinarian prescribes an antibiotic to a dog based on its weight. The effective dosage of the antibiotic is given by [tex]\( d \geq \frac{1}{5} w^2 \)[/tex], where [tex]\( d \)[/tex] is the dosage in milligrams and [tex]\( w \)[/tex] is the dog's weight in pounds.

Which of the following ordered pairs gives an effective dosage of antibiotics for a 35-pound dog?

A) [tex]\( (35, 260) \)[/tex]
B) [tex]\( (240, 35) \)[/tex]
C) [tex]\( (260, 35) \)[/tex]
D) [tex]\( (35, 240) \)[/tex]



Answer :

Sure, let's solve this question step-by-step:

1. Identify the Given Information:
- Dog's weight, [tex]\( w = 35 \)[/tex] pounds.
- The formula for the effective dosage, [tex]\( d \geq \frac{1}{5} w^2 \)[/tex].

2. Calculate the Effective Dosage:

Substitute [tex]\( w = 35 \)[/tex] into the formula:
[tex]\[ d \geq \frac{1}{5} \times (35)^2 \][/tex]

Calculate [tex]\( (35)^2 \)[/tex]:
[tex]\[ 35 \times 35 = 1225 \][/tex]

Now, calculate [tex]\( \frac{1}{5} \)[/tex] of 1225:
[tex]\[ \frac{1}{5} \times 1225 = \frac{1225}{5} = 245 \][/tex]

Therefore, the effective dosage is:
[tex]\[ d \geq 245 \text{ milligrams} \][/tex]

3. Evaluate Each Ordered Pair:

- Option A: [tex]\( (35, 260) \)[/tex]

Here, the dosage [tex]\( d = 260 \)[/tex].

Check if [tex]\( 260 \geq 245 \)[/tex]:
[tex]\[ 260 \geq 245 \quad \text{(True)} \][/tex]

This pair provides an effective dosage.

- Option B: [tex]\( (240, 35) \)[/tex]

Here, the dosage [tex]\( d = 240 \)[/tex].

Check if [tex]\( 240 \geq 245 \)[/tex]:
[tex]\[ 240 \geq 245 \quad \text{(False)} \][/tex]

This pair does not provide an effective dosage.

- Option C: [tex]\( (260, 35) \)[/tex]

Here, the dosage [tex]\( d = 260 \)[/tex].

Check if [tex]\( 260 \geq 245 \)[/tex]:
[tex]\[ 260 \geq 245 \quad \text{(True)} \][/tex]

This pair provides an effective dosage.

- Option D: [tex]\( (35, 240) \)[/tex]

Here, the dosage [tex]\( d = 240 \)[/tex].

Check if [tex]\( 240 \geq 245 \)[/tex]:
[tex]\[ 240 \geq 245 \quad \text{(False)} \][/tex]

This pair does not provide an effective dosage.

4. Conclusion:

Based on the calculations, the ordered pairs that give an effective dosage of antibiotics for a 35-pound dog are:
- Option A: [tex]\( (35, 260) \)[/tex]
- Option C: [tex]\( (260, 35) \)[/tex]

Therefore, the answer is:

- A) [tex]\( (35, 260) \)[/tex]
- C) [tex]\( (260, 35) \)[/tex]