Question

A doctor prescribes an ointment that is 4% hydrocortisone. A pharmacist has 1% and 5% concentrations in stock. How many ounces of each should the pharmacist use to make a 5-ounce tube?.

Answer 1

Answer:

$1.25$ ounes of $1$% and $3.75$ ounes of $5$% will be used to make a $5$-ounce tube

Explanation:

let "x" represent the number of ounces of  $1$% concentration

Then the number of ounces of  $5$%concentration would be $5-x$

Now the total of ounces of  $1$% and  $5$% would be equal to $5$-ounce of $4$% hydrocortisone.

so the equation will be

$0.01 (x) + 0.05(5-x) = 0.04*5\\0.01x-0.05x+0.25= 0.2\\\\0.25-0.2= 0.04x\\x = \frac{0.05}{0.04} \\x= 1.25\\5-x= 5-1.25 = 3.75$

hence

$1.25$ ounes of $1$% and $3.75$ ounes of $5$% will be used to make a $5$-ounce tube