The manager of a sports shop intends to purchase some badminton rackets. The demands for the rackets are 50, 60, or 70. He can either order 50, 60, or 70 rackets at RM80 each. He sells each racket for RM120. However, if there are unsold rackets at the end of the year, the manager will return the rackets to the supplier at RM70 each. Construct a payoff table. Determine the number of rackets that the manager should order according to :
(a) Maximax criterion
(b) Maximax criterion
(c) Equally likely criterion