Question #2766f

1 Answer
Ernest Z.
Jan 30, 2015

There are 5.25 × 10⁷ cells/mL in the original sample.

Step 1. Find the volume of a box.

I assume that the depth of the box is 0.1 mm. Then

V=Ah=125mm2×0.1 mm=4×10−3mm3=4×10−6mL

Note: 1 mL = 1 cm³ = 1000 mm³.

Step 2. Calculate the concentration of cells in a box.

Concentration=cellsmillilitres=7 cells4×10−6mL=1.75×106cells/mL

Step 3. Correct for the dilution factor (DF).

Your original sample was 30 times more concentrated (DF = 30).

Original concentration = DF × concentration in slide box = 30 × 1.75 × 10⁶ cells/mL = 5.25 × 10⁷ cells/mL

The original sample contained 5.25 × 10⁷ cells/mL.

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