Question

Which of the following situations is an example of direct proportions ? The perimeter P of a square and its side length a The length l and width b of a rectangle, given the area remain constant The number of units of a product that can be purchased given a fixed amount of money and unit price of the product The number of rows m and the number of columns n in which a fixed number of marbles can be arranged.
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Answer 1

Answer:

The situation 1. is an example of direct proportion

Step-by-step explanation:

1. P = 4a

Then $P \propto a$

2. A=lb =k ( constant)

l= k/b

$L \propto\frac1 b$

3. Let fixed amount is m ,no of units are n and unit price=p

Then unit price= Fixed amount/ no of units

p=m/n

m is a constant

$p \propto\frac1 n$

4 Fixed no of marbles N= m × n

n= N/m

N is a constant

$n \propto\frac1 m$

Thus situation 1. is an example of direct proportion