Naplex math/SD 120 qs DIRE help

[Pharmacygrad3741]

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Hi there! I'm having a lot of difficulty with figuring out when to do allegation or use a ratio - such as the problems on the SDN 120 like #12 and, #30, #78. For example #12 on the SD 120 I solved it setting up ratios and cross multiplying Iv can't seem to understand why if I'm they're both the same drug/solution (I.e dextrose) and I know the the percentages of both and the volume of one, why can't I set up equivalent ratios and cross multiply? I set up and solved #12 on the sd120 like this:
1) I need 10% which is 10g/100mL = x/1000mL (total IV is 1L)
X= 100g needed
2) if I need 100g, how many mLs of the 70% dextrose will I need so:
70g/100mL = 100g/x
X = 142.9mL needed
--- this is way off from the answer key as they used allegation. However I'm SO confused as to when to set up direct ratios like I did above and when I need allegation. I get every single one wrong, because I'm not grasping the concept. Please help if you can my exam is in 4 days and I'm borderline panic attack 🙁

 

[maria1oh]

Question 11 is connected so make sure u account for that volume so the total is not 1000 still. In fact we don't know what the total volume will be since we haven't added the dextrose yet so use alligation.
Remember to read the instructions above question 11 mentioning question 11-13 are all connected.

Don't worry the naplex math is not this difficult. I would recommend using rxprep or prontopass for the math review. They are more realistic to what you will see on naplex.

Also have you taken the pre-naplex yet?

 

[Pharmacygrad3741]

Question 11 is connected so make sure u account for that volume so the total is not 1000 still. In fact we don't know what the total volume will be since we haven't added the dextrose yet so use alligation.
Remember to read the instructions above question 11 mentioning question 11-13 are all connected.

Don't worry the naplex math is not this difficult. I would recommend using rxprep or prontopass for the math review. They are more realistic to what you will see on naplex.

Also have you taken the pre-naplex yet?

Hi thank you so much for replying! I actually did know they were connected (so 1015 mL) but I was just trying to show you my understanding of how to solve questions like that, when the volume is given. But I actually tried pronto pass first and got almost all of their allegation/ratio questions wrong for this same reason! I had a hard time understanding how they do their problems so was hoping to figure it out from the Sd120 problems. But you said the math isn't that bad? Have you taken the Naplex recently? Because I did hear that it's changed quite a bit, I'm just not sure what to focus on. As for Rxprep are you referring to the book examples? Bc I felt as though they were too simple, but I'm not sure. Thank you so so much for replying and for your advice!

 

[Pharmacygrad3741]

Question 11 is connected so make sure u account for that volume so the total is not 1000 still. In fact we don't know what the total volume will be since we haven't added the dextrose yet so use alligation.
Remember to read the instructions above question 11 mentioning question 11-13 are all connected.

Don't worry the naplex math is not this difficult. I would recommend using rxprep or prontopass for the math review. They are more realistic to what you will see on naplex.

Also have you taken the pre-naplex yet?

And no I haven't taken the prenaplex yet! I was too nervous too, seeing as if I do poorly my confidence will be shot, but I'm planning on taking it tomorrow

 

[maria1oh]

Rxprep also has the quiz bank for calculations but the book covers the important stuff.
Also I glanced at the other two problems you mention and those are also cases where you don't know the total volume so use alligation to find out about the parts.
You will be fine! I promise you will pass!