If accuracy is not a problem the most simple way to produce 20 ml of a 1:400 dilution is to take 1:400 of 20 ml (i.e. 0.05 ml) of the original solution and add 19.95 ml of liquid.
As pipettes are the most precise close to their maximum uptake volume and micro-pipettes are inherently much less precise than pipettes for larger volumes I'd do a two-step dilution.
1. step: 1.000 ml of original solution with 1 ml pipette + 4 times 4.750 ml with 5 ml pipette
2. step: 1.000 ml of solution from step 1 + 4 times 4.750 ml with 5 ml pipette.
When 0.25 ml is diluted to a final volume of 20 ml, the resulting dilution can be calculated as the ratio of the original volume to the final volume. This is calculated as 0.25 ml / 20 ml, which simplifies to a dilution factor of 1:80. Therefore, the resulting dilution is 1:80.
1 ml solute to 19 mls solvent. This gives a total volume of 20 (20 fold)
20 reams or 10,000 sheets of 20 lb paper would weigh approximately 100 pounds.
The mass of the substance is 20 grams in a 10 ml sample. Therefore, the substance has a density of 2 grams/ml. For a 200 ml sample of the same substance, the mass would be 400 grams (200 ml x 2 grams/ml).
Multiply the two dimensions to get the area. The calculation will give you 80 square feet.
Add 2 mL of culture to 20 mL of buffer. 2/20 = 1/10
400x1.20=480
400 ÷ 20 = 20 hours (though it is unlikely that the speed would be constant!)
100
0.05
400
20 and -20
20 out of 400, as a percentage = 100*(20/400) = 5%
It would be a 20 by 20 ft square
400 - 20 = 380
To achieve a 20 to 1 dilution ratio in a laboratory setting, you would mix 1 part of the substance you want to dilute with 19 parts of the diluent (usually water or another solvent). This will result in a total of 20 parts, with the original substance being diluted by a factor of 20.
The answers are sqrt(400) = -20 or +20The answers are sqrt(400) = -20 or +20The answers are sqrt(400) = -20 or +20The answers are sqrt(400) = -20 or +20