Dosage Calculations

I'm needing a little guidance with a few problems i'm not sure about. We're using the factoring method and i've factored them but maybe it's just me but it didn't seem right.

Order: Dalmane gr. ss po hs

Supply: Dalmane 30 mg capsules

Amount to be given?

1 cap x 60mg/30 mg x 1 gr = 2 capsules

Order: Atarax 30 mg po bid

Available: Atarx syrup 10 mg per tsp

Give how many tab(s)?

1 mL x 30 mg/ 10 mg = 3 mL

All the other problems I felt great about but when I went back to these two I felt as if I was missing something, not sure?

There is one last problem I solved and i'm positive the answer is right but the second part threw me off.

Order: Codeine gr 1/4 IM q4h prn

Codeine 30 mg per mL is on hand in a single dose Carpojet syring.

How many mL would you administer?

How many mL would you waste?

I came up with administering 0.5 mL

For the waste part I first came up with 29.5 then going back over I came up with 0.5 mL which i'm almost positive is right just need a little reassurance i'm doing it correctly!

Thanks in advance for any help! I'm not asking for anyone to solve the problems for me, I just want to make sure i'm in the correct path of doing the problems :)