62. True Explanation: Marginal rate of substitution is defined as ratio of margi

62. True
Explanation: Marginal rate of substitution is defined as ratio of marginal utility of X and marginal utility of Y. Combining this fact with law of diminishing marginal utility we find that as we consume more of X in exchange of Y marginal utility of X decreases whereas marginal utility of Y increases and thereby marginal rate of substitution which is the ratio of marginal utility of X and marginal utility of Y diminishes as we consume more of X in exchange of Y.63. False
Explanation: because at the saturation point of any commodity total utility is maximum and therefore marginal utility should be zero not positive at the saturation point.
64. True
Explanation: At the optimal choice of any consumer following condition must be satisfied:
Since it is given that = 3 so this condition will be satisfied only when price of Y is thrice of price of X. Hence the given statement is correct.65. False
Explanation: because two substitute goods are always substituted in fixed ratio and that fixed ratio is called marginal rate of substitution. Since marginal rate of substitution can be defined as the ratio of marginal utilities as well so the ratio of marginal utilities will also be fixed not decreasing in case of two substitute goods.