Dosage calculation question for second year nursing student

[Samm06, BSN, RN]

Question: Explain how you would prepare each of the following from ready-to-use nutritional formulas for the specified time period. Note which supply would require the least waste of unused product.

ORDER: 1/2 strength Sustacal 250 mL p.o. q.i.d.

SUPPLY: Sustacal 5 and 10 fl oz

Here is what I understand:

1,000 mL needed for daily supply (250 mL x 4 times a day = 1,000 mL total)

500 mL Sustacal + 500 mL water = 1,000 mL 1/2 strength Sustacal

Here is my problem:I don't understand how the book came up with two 10 fl oz cans and to discard 100 mL.

The book doesn't provide any kind of solution on how to come up with these answers, if someone could please help me, I would greatly appreciate it.

[loriangel14, RN]

There are 30 mls in an ounce. A 10 ounce can will have 300 milliliters in it, giving you 600. You need 500.

[Samm06, BSN, RN]

so that equals only ONE 10 fl oz can right? that is what i got before. However the answer in the back of the book says to use TWO 10 fl oz cans and discard 100mL, how is that possible? I'm really confused on that part.

[loriangel14, RN]

300 in each can. 2 cans is 600. You need 500.

[Samm06, BSN, RN]

thank you so much. that was actually easy. so with a 5 fl oz can that would be 150 mL per can, if i go to 3 cans that is only 450 mL (when i need 500 mL) , and then 4 cans would be 600 mL (too much again), but because that is so many cans and the question is asking for the least waste of unused product, I wouldn't choose that option correct? because with the 10 fl oz cans that only requires 2 cans vs 4 cans of the 5 fl oz correct?

[dudette10, MSN, RN]

nevermind. I confused myself. Ha!

[Samm06, BSN, RN]

Okay because I thought I was going crazy and almost had a mental breakdown but then I remembered seeing this website before and so i decided to post on it, and you guys have been helpful so far :)

[loriangel14, RN]

Well yeah generally you will use the larger cans and just use two.

[Samm06, BSN, RN]

Your book's answer is incomplete. Technically, you would discard 100 ml after dilution from each of two cans for a total of 200 ml waste each day. I can see where the answer given is confusing; it confuses me too.

However, maybe the "READY-TO-USE" in the question is where it's trying to say no dilution is needed? maybe? i don't know.

[Samm06, BSN, RN]

Well yeah generally you will use the larger cans and just use two.

Thank you.

[Samm06, BSN, RN]

Is this reference to the post you said where the book is "incomplete"? just wanted to clarify lol

[Samm06, BSN, RN]

nevermind. I confused myself. Ha!

is this reference to the post you said where the book is "incomplete"? just wanted to get clarification.