Question

Which of the following line represents the proportional relationship between time and amount of money you spent?

• A. Line 2
• B. Line 4
• C. Line 1
• D. Line 3

Answer 1

The correct option is D Line 3

x and y said to be proportional relationship, if

i) The ratio between y and x is constant.
ii) The graph of the function passes through the origin (0,0).

Let us consider Line 1:


Slope is constant as it is a straight line.
It does not pass through the origin (0,0).
Therefore, it is not representing a proportional relationship.

Let us consider Line 2:


Slope is constant as it is a straight line.
It does not pass through the origin (0,0).
Therefore, it is not representing a proportional relationship.

Let us consider Line 3:


Slope is constant as it is a straight line.
It does pass through the origin (0,0).
Therefore, it reprsents a proportional relationship.

Let us consider Line 4:


Slope is not constant as it is not a straight line but at (1,20) slope becomes 0.
It also passes through the origin (0,0).

Therefore, it is not reprsenting a proportional relationship.

So, only Line 3 represents a proportional relationship.