Rx: Ceftriaxone 500 mg IVPB in DSW 50 ml, infuse over 30 min q12h. The 2-g ceftriaxone vial states that if you reconsti- tute with 8.6 ml, the resulting final volume of the vial is 10 ml. a. How much diluent would be added to obtain a vial concentration of 1 g/10 mL? b. If the vial is diluted to 1 g/10 mL, how much drug would be drawn up for one dose? c. How many doses are available in one 2-g vial? d. How many vials would be needed to prepare a 7-day supply? e. If you were preparing a 7-day supply, how many 20-mL vials of sterile water would you need to reconstitute the ceftriaxone vials? f. If the 500-mg dose is added to DSW 50 ml, what is the total volume of one IVPB?

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the   (original price) is $420.

0.7x   = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.  

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

equation image indicator

x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

i think c. but don't trust it.

step-by-step explanation: