word problem help, converting measurements

**question 1) You need to give 1g of erythromycin orally. You have erythromycin suspension 250mg in 5ml. How much of the suspension do you need to give? ( 1000mg = 1g) **

so we have 250mg in 5ml, and i need to give 1g,

so is it

$\displaystyle 250 \times 4 = 1000 $

so 1000mg = 20 ml?

So I need to give 20ml?

**question 2) you are to administrator a drug to a patient that comes in strength 1 in 100, you need to give the patient 200mg of the drug. how man ml would you need to prepare? (1 in 1000 means 1g in 1000ml, )**

Am not sure how to to this one,

if 1 in 100 means, 1g in 100ml, than 200mg is gong to be 0.2g in 20ml, so is it 20ml I need to give?

thank you,

Re: word problem help, converting measurements

You have found the correct answers. You may want to set up ratios to solve the problems, so that you have a method that is easy to use when you can't just "eyeball" the answers.

1.) $\displaystyle \frac{5}{250}=\frac{x}{1000}$

$\displaystyle \frac{1}{50}=\frac{x}{1000}$

$\displaystyle x=\frac{1000}{50}=20$

2.) $\displaystyle \frac{1}{100}=\frac{0.2}{x}$

$\displaystyle \frac{1}{100}=\frac{1}{5x}$

$\displaystyle 5x=100$

$\displaystyle x=20$

Re: word problem help, converting measurements

Quote:

Originally Posted by

**Tweety** **question 1) You need to give 1g of erythromycin orally. You have erythromycin suspension 250mg in 5ml. How much of the suspension do you need to give? ( 1000mg = 1g) **

so we have 250mg in 5ml, and i need to give 1g,

so is it

you must define the concentration of what you have. $\displaystyle 250 \times 4 = 1000 $

so 1000mg = 20 ml?

So I need to give 20ml?

**question 2) you are to administrator a drug to a patient that comes in strength 1 in 100, you need to give the patient 200mg of the drug. how man ml would you need to prepare? (1 in 1000 means 1g in 1000ml, )**

Am not sure how to to this one,

if 1 in 100 means, 1g in 100ml, than 200mg is gong to be 0.2g in 20ml, so is it 20ml I need to give?

thank you,

you must define the concentration of your stock