# Math Help - mixing

1. ## mixing

1.If 0.5ml of serum is mixed with 1.0ml of water and a glucose test is performed resulting in a reading of 200mg/dl from the instrument, what is the final reported result?

2.If a 1:5 dilution is made with 0.5 ml of serum, how much water is used?

3.You are given a series of ten tubes, each of which contain 5ml of diluents. To the first tube is added 1ml of serum, and a serial dilution using 1ml is carried out in the remaining tubes. what is the serum concentration in tubes 4 and 8?

2. ## Med stuff

Patient has diabetes mellitus.
Anything more than 140 mg/dL is considered as diabetes mellitus.

3. ## yes thats true

yes that is true but i need to try to work this problem. Thank you very, very much for your reply. It is informativeand is relative, but not the answer needed in this particular problem.

4. Originally Posted by labrat
1.If 0.5ml of serum is mixed with 1.0ml of water and a glucose test is performed resulting in a reading of 200mg/dl from the instrument, what is the final reported result?
Ummm... 200 mg/dL? Reported result of what, specifically?

-Dan

5. Originally Posted by labrat
2.If a 1:5 dilution is made with 0.5 ml of serum, how much water is used?
$\frac{1}{5} = \frac{0.5~mL}{x}$

So
$x = 5 \cdot (0.5~mL) = 2.5~mL$

-Dan

6. Originally Posted by labrat
3.You are given a series of ten tubes, each of which contain 5ml of diluents. To the first tube is added 1ml of serum, and a serial dilution using 1ml is carried out in the remaining tubes. what is the serum concentration in tubes 4 and 8?
The first tube contains 5 mL of dilutent (solvent?) and 1 mL serum. We take 1 mL of solution from this so we have
$\frac{1}{5} = \frac{x}{1~mL}$

$x = 0.2~mL$
we are taking 0.2 mL of serum from tube 1.

We mix this into 5 mL of dilutent in tube 2. Then take 1 mL of solution from this and put it into tube 3, etc.

Each time we do this we are reducing the amount of serum by a factor of 5. So the amount of serum s, in each tube t is going to be of the form:
$s_t = (1~\text{mL serum}) \left ( \frac{1}{5} \right ) ^t$

So in tube 4 we have
$s_4 = (1~\text{mL serum}) \left ( \frac{1}{5} \right ) ^4 = 0.0016~mL$

So the concentration in tube 4 is $\frac{0.0016~\text{mL serum}}{5~\text{mL dilutent}}$

and in tube 8 we have
$s_8 = (1~\text{mL serum}) \left ( \frac{1}{5} \right ) ^8 = 2.56 x 10^{-6}~mL$

So the concentration in tube 8 is $\frac{2.56 x 10^{-6}~\text{mL serum}}{5~\text{mL dilutent}}$

-Dan

7. ## Thanks a Bunch

Thank you so very much. You have been a big help. Im in my first semester of college and struggling.I really appriciate your help so much.

8. Originally Posted by labrat
Thank you so very much. You have been a big help. Im in my first semester of college and struggling.I really appriciate your help so much.
No problem! Glad I was able to help.

-Dan