Can you work this out?

[Marika]

I can't get it for the life of me!

If 15 grams of a 1% ointment are combined with 30 grams of a 2.5% lotion, what is the % of the final strength?

Thanks in advance. Taking the PTCB Thurs. morning. The more I get it then something like this comes along & goes right over my head!

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[killerpenguin21]

i believe it should be...

15g of 1% = 0.15g
30g of 2.5% = 0.75g
0.75g + 0.15g = 0.9g

0.9g/45g= x/100

final answer = 2%

 

[Marika]

I've taught myself the calculations on my own. Which is a feat! If I have the answer I can usually figure out how to arrive at it. Some like this I have trouble with. Thanks again.