What kind of questions can be answered?
Question 1You have in stock a 30gram tube of 1% hydrocortisone cream and a 45 gram tube of 2.5% hydrocortisone cream and you need to prepare a 30 gram tube of  2% hydrocortisone. How much of each tube do you use to create this new concentration?
Question 2: You need a 200 ml stock solution of 10mg/ml aminophylline to prepare several unit-dose oral syringes. You carry the standard 25mg/ml aminophylline solution. How much water and standard aminophylline (25 mg/ml) do you combine to create this new solution?
Question 3: You need to create 250 ml bags containing 10% dextrose. You have in stock 250ml
     bags of D5W, and also syringes containing 50% dextrose (D50). How much of each
     do you use to create exactly 250ml of 10% dextrose?
Question 4: How much water should you mix with 70% isopropyl alcohol to make 500 ml
    of 20% alcohol?
Question 5: You need a 250 ml bag with normal saline, and 0.0625% of bupivacaine and 5 mcg/ml
fentanyl. The total volume must equal 250ml and you have in stock 0.25% bupivacaine
vials and 50 mcg/ml - 5 ml amps of fentanyl. How much 0.25% bupivacaine do you need,
and how much saline must be removed from the 250 ml IV bag?

Note: must enter zero under normal saline because normal saline is just a diluent in this case. It contains 0% of bupivacaine. Fentanyl requires a separate calculation-- need 5 mcg/ml x 250ml = 1250 mcg total.    1250 divided by 50mcg/ml= 25 ml.   Remove an additional 25 ml of saline from the bag, and then add the 63 ml of bupivacaine as mentioned below, plus 25 ml of Fentanyl (using the 50 mcg/ml ampules).