# NCERT Class 8 Mathematics Solutions: Chapter 13 – Direct and Inverse Proportions Exercise 13.1 Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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

Answer:

Consider enlarged length of bacteria be

Actual length of bacteria

 Length Enlarged length

Length and enlarged length of bacteria are in direct proportion.

So, the enlarged length of bacteria is

2. In a model of a ship, the mast is high, while the mast of the actual ship is high. If the length of ship is , how long is the model ship?

Answer:

Consider the length of model ship be

 Length of actual ship (in m) Length of model ship (in cm)

Here, length of mast and actual length of ship are in direct proportion.

So, the length of the model ship is .

3. Suppose of sugar contains crystals. How many sugar crystals are there in

(i) of sugar?

(ii) of sugar?

Answer:

(i) Consider,

Sugar crystals be .

 Weight of sugar (in kg) No. of crystals

Table title: In table weight of sugar and No. of crystals

Table description: In table weight of sugar and No. of crystals

Weight of sugar and number of crystals are in direct proportion.

So, the number of sugar crystals is

(ii) Consider sugar crystals be .

 Weight of sugar (in kg) No. of crystals

So, the number of sugar crystal is

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