The table below shows the workers engaged by an agricultural firm over a period of time. Study it and answer the questions that follow;

Number of workers	Total product	Marginal product	Average product
0	0	0	0
1	20	20	20
2	50	30	z
3	70	20	23.3
4	80	y	20
5	80	0	16
6	x	-9.8	11.7

(a) Calculate the values of X, Y, and Z.

(b) At what level of employment of labour does the firm experience:

i. increasing returns 
ii. decreasing returns 
ii. negative returns

(c) State the law of diminishing returns

(d) i. On a graph sheet, draw the total product and marginal product curves.

ii. State any two relationships between the two curves in (d)(i) above