# NCERT Solutions Class 8 Mathematics Solutions for Exercise 13.1 in Chapter 13 - Direct and Inverse Proportions

Question 9 Exercise 13.1

Q5) 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, want would be its enlarged length?

Solution:

Let the actual length of bacteria be x cm and the enlarged length of bacteria be y cm if the photograph is enlarged for 20,000 times.

The given information in the form of a table is as follows.

The number of times the photograph of bacteria was enlarged and the length of bacteria are in direct proportion.

Therefore, we obtain

\frac{5}{50000}=\frac{x}{1}

\Rightarrow x=\frac{1}{10000}=_{10}-4

Hence, the actual length of bacteria is _{10}-4 cm.

Let the length of bacteria when the photograph of bacteria is enlarged 20,000 times be y.

\frac{5}{50000}=\frac{y}{20000}

y=\frac{20000\times5}{50000}=2

Hence, the enlarged length of bacteria is 2 cm.

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