transformation efficiency

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transformation efficiency

Hey i tried several methods to calculate transformation efficiency..pls anyone help me pls..

50 ul of competent E.coli cell (10^9 cfu/cell)  were transformed using 0.5 ng of plasmid DNA , to which 950 ul of SOS medium was added.only 50 ul was plated and after 12 hrs of incubation 90 colonies were observed.what is the transformation efficiency?

pls tell me the correct formula and way to use it

what is the percentage of transformtion..?

pls help

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 Calculation of Transformation Efficiency (Colony Forming Units [cfu])

Transformation efficiency is defined as the number of colony forming units
(cfu) produced by 1
DNA) and is measured by performing a control transformation reaction using a
known quantity of DNA, typically 0.1ng, then calculating the number of cfu
formed per microgram DNA.
μg of Competent Cells Control DNA (supercoiled plasmid
concentration of 0.1ng/
The Competent Cells Control DNA (pGEM®-3Z Vector) is supplied at aμl in TE buffer.
Equation for Transformation Efficiency (cfu/
cfu on control plate × 1 × 10
ng of Competent Cells Control DNA plated

After adding 900
transformed with 0.1ng Competent Cells Control DNA, transfer 100
(equivalent to 0.01ngDNA) to 900
(equivalent to 0.001ng DNA). If 100 colonies are observed on the plate, the
transformation efficiency is:
100cfu × 1 × 10
μl of SOC medium to 100μl of competent cells that have beenμlμl of SOC medium and plate 100μl3ng = 1 × 108 0.001ng μg cfu/μg
than transformation with supercoiled plasmid DNA. 
Transformation with ligated plasmid DNA will produce fewer colonies