explain the law of variable proportion …

Law of variable proportion states the impact of change in units of a variable factor on the physical output. When more and more units of a variable factor are combined with a fixed factor then total product increases at increasing rate in the beginning, then increases at decreasing rate and finally it starts falling.
Phase I : TP increases at an increasing rate.
Phase II : TP increases at diminishing rate.
Phase III : TP falls.
Behaviour of MP
Phase I: MP increases and becomes maximum.
Phase II: MP decreases and becomes zero.
Phase III: MP becomes negative

First Phase : TPP increases with increasing rate upto A point. MPP also increase and becomes maximum at point C.
Second Phase : TPP increases with diminishing rate and it is maximum at point B. MPP start to decline and becomes zero at D point.
Third Phase : TPP starts to decline and MPP becomes negative.

• Important instruction for giving the answer of above question.
• Do not use diagram for the explanation of this question if it is instructed to use schedule and do not use schedule if the explanation of this question asked with the help of diagram.
• Do not explain the behaviour of marginal product with the help of schedule and diagram. If there is instruction to explain only the behaviour of total product.
• Do not explain the behaviour of total product with help of schedule and diagram if there is instruction to explain only the behaviour of marginal product.