Solution Found!
Yeast cells are suspended in a liquid medium. A 2 mL
Chapter 4, Problem 13SE(choose chapter or problem)
Yeast cells are suspended in a liquid medium. A 2 mL sample of the suspension is withdrawn. A total of 56 yeast cells are counted.
a. Estimate the concentration of yeast cells per mL of suspension, and find the uncertainty.
b. What volume of suspension must be withdrawn to reduce the uncertainty to 1 cell per mL?
Questions & Answers
QUESTION:
Yeast cells are suspended in a liquid medium. A 2 mL sample of the suspension is withdrawn. A total of 56 yeast cells are counted.
a. Estimate the concentration of yeast cells per mL of suspension, and find the uncertainty.
b. What volume of suspension must be withdrawn to reduce the uncertainty to 1 cell per mL?
ANSWER:
Solution :
Step 1 of 2:
Given,
A sample of the suspension is withdrawn is 2 ml and
So t=2 ml.
The number of yeast cell counted is 56.
So X=56.
Our goal is :
a). We need to estimate the concentration of yeast cell per ml of suspension and find the
Uncertainty.
b). We need to find what volume of suspension must be withdrawn to reduce the uncertainty
to 1 cell per ml.
a).
Now we have to estimate the concentration of yeast cell per ml of suspension.
Then we have to find the uncertainty.
Then the estimate the concentration of yeast cell per 1 ml is
We know that t=2 and X=56.
Therefore the estimate the concentration of yeast cell per 1 ml is 28.
Then we have to find the uncertainty.
The uncertainty is is
We consider .
Then substitute values.
Therefore the the uncertainty is 3.7416.
Hence .