You need to dilute some pure (100%) ethanol to make a 70% (v/v) solution for disinfecting your work area.

You will make 200ml of your 70% (v/v) solution.  How much pure ethanol will you need in ml?  (You do not need to include units in your answer.)

You need to prepare 1.25L of Tyrode's Solution (Acidic).  The components of this solution are:

• 0.1368M Sodium chloride (Mw: 58.44)
• 0.002686M Potassium chloride (Mw: 74.55)
• 0.001632M Calcium chloride dihydrate (Mw: 147.01)
• 0.0004918M Magnesium chloride hexahydrate (Mw: 203.3)
• 0.00555M Glucose (180.16)
• 0.0001M Polyvinylpyrrolidone (Mw: 40000)

You have a cell suspension for which you need to determine the cell concentration.  You have stained your cells with white cell diluting fluid, using 20μl of cell suspension and 40μl of white cell dilution factor.

Your counts for each of the outer squares are:

1. 56
2. 73
3. 74
4. 70

What is the cell concentration for your sample? (You need to answer in standard notation, e.g. 4500 rather than 4.5×10³.)  (You must include units in your answer.)

You have a cell suspension for which you need to determine the cell concentration.  You have stained your cells with trypan blue, using 20μl of cell suspension and 40μl of trypan blue.  Trypan blue stains dead cells blue, while live cells exclude this dye.

Your counts for each of the outer squares are:

1. Viable: 102; Dead: 26
2. Viable: 103; Dead:18
3. Viable: 117; Dead: 28
4. Viable: 109; Dead: 21

What is the percentage of viable cells in your sample?  Answer to 1 decimal place.