Anson cannot detect any weight below 0.22 g. He can perceive a weight of 5 g as 6 g. He can just distinguish a heavier weight of 9 g from a reference weight of 8 9. Suppose his perception follows Weber's law and Stevens' power law with a linear response, (a) calculate the range of error perceived by him for a weight of 20 g; {4 marks} (b) find a mathematical expression for his perception on weight, hence find the actual weight when he perceives the weight as 20 g