Question

A photograph of a bacteria enlarged 50,000 times attains a length of 5 cm as shown in the diagram. What is the actual length of the bacteria? If the photograph is enlarged 20,000 times only, what would be its enlarged length?

Answer 1

Let the enlarged length of bacteria be $x$.
Actual length of bacteria =
$\frac{5}{50000}=\frac{1}{10000}cm={10}^{-4}cm$

$\begin{array}{ccc}Length& 5& x\\ Enlargedlength& 50,000& 20,000\end{array}$

Here length and enlarged length of bacteria are in direct proportion.
$\therefore \frac{5}{50000}=\frac{x}{20000}\Rightarrow x\times 50000=5\times 20000\Rightarrow x=\frac{5\times 20000}{50000}=2cm$
Hence, the enlarged length of bacteria is 2 cm.