Solution
Let the enlarged length of bacteria be x.
Actual length of bacteria = 5/50000 = 1/10000 cm = 10-4 cm
Since the length of bacteria is directly proportional to the number of times the photograph is enlarged,
The actual length is 10-4 cm
And, 5/50000 = x/20000
x = 2 cm
Answer
The enlarged length is 2 cm