I used the tract method to solve this problem. it's easier this way for me. You can see all the factors you need to use. You also use this method when calculating drops per min.
How to set it up: 800 ml 1 hr -------|--------- 12 hr 60 min
Next cancel out the common factors and multiply across.
800ml ------ 720min
Divide and solve. Answer 1.11 ml/min
May 05, 2011
This is not so bad by: Anonymous
or you can do it this way: Change the 12 Hours to mins by mulitplying 60 mins
12 x60 = 720 mins
Divide the volume 800ml by 720min
800 ml/720 min =1.11 ml/min
Feb 28, 2011
Got it! by: Judi
Thanks Keith - I needed that!
Feb 28, 2011
Response to Anonymous by: Judi
I understand how the end result is achieved but here is where I'm stuck: How in the name of heaven do you get 66.7??? I divide 12 into 800 & I get 66.6 - every time. I cannot go any further with the problem until I understand the 66.7. Please help before I am completely bald from pulling my hair out!
Reply (by Keith)
Hi Judi, I don't want you to lose anymore hair over this problem ;)
On my calculator:
800 ÷ 12 = 66.666667
When you're doing these calculations, most of the time you want to round up the 1st or 2nd digit after the decimal.
In this case that becomes:
66.7
What determines the number of places you want to round to (in Chemistry) is how many numbers are in the largest factor of the problem. In this case that number is 800, which has 3 digits in it, so your answer needs to have 3 digits. If we were dealing with 8000, then the answer should be 66.67. These are called significant figures.
As far as dealing with the questions on this site and on the exam, if you are off by 0.1 in your answer, it's nothing to split hairs over since answers are multiple choice. Yet, when you're compounding in the field then it will be vital to be completely accurate.
Feb 24, 2011
Missing a small but important detail by: Judi
Please break this down some more. I keep getting 1.17 ml/minute. How do we arrive @ 1.11 ml/minute? Somebody help!
Feb 12, 2011
ml/min by: Anonymous
800ml / 12 hrs = 66.7 ml/hr divided by 60 mins = 1.11ml/min
