Introduction:
When a consumer is buying only one commodity, the equilibrium position is reached when the consumer maximizes their satisfaction or utility. This equilibrium is determined by the consumer's marginal utility schedule, which tracks the additional utility gained from consuming each additional unit of the commodity.

Marginal Utility Schedule:
The marginal utility schedule represents the relationship between the quantity consumed of a commodity and the marginal utility derived from each additional unit. It shows how the consumer's satisfaction changes as they consume more of the commodity.

Equilibrium Position:
To reach the equilibrium position, the consumer will continue to consume additional units of the commodity until the marginal utility derived from the last unit consumed equals the price of the commodity. At this point, the consumer has maximized their utility given the price of the commodity.

Consumer Behavior:
1. Law of Diminishing Marginal Utility: According to this law, as the consumer consumes more units of a commodity, the marginal utility derived from each additional unit decreases. This means that the consumer gains less satisfaction from each additional unit consumed.

2. Decreasing Marginal Utility: The marginal utility schedule shows that as the consumer consumes more units, the marginal utility decreases. For example, if a consumer consumes 1 unit, the marginal utility may be 10. But when the consumer consumes the 2nd unit, the marginal utility may decrease to 8.

3. Price and Marginal Utility: The consumer will compare the price of the commodity with the marginal utility derived from consuming each additional unit. The consumer will continue to consume as long as the marginal utility is greater than or equal to the price.

4. Reaching Equilibrium: The consumer will keep consuming until the marginal utility of the last unit consumed equals the price. At this point, the consumer has maximized their satisfaction given the price of the commodity. If the consumer consumes more units, the marginal utility will be less than the price, leading to a decrease in overall utility.

Conclusion:
The consumer reaches the equilibrium position when they consume additional units of the commodity until the marginal utility of the last unit consumed equals the price. This ensures that the consumer maximizes their satisfaction given the price of the commodity. The marginal utility schedule helps track the changes in satisfaction as the consumer consumes more units, allowing them to make informed decisions about their consumption.