**Introduction**

In economics, the concept of equilibrium refers to the point at which the demand and supply for a commodity are balanced. In the case of a consumer buying only one commodity, reaching equilibrium means that the consumer has maximized their satisfaction or utility from consuming that commodity. To understand how a consumer reaches equilibrium, we can analyze their marginal utility schedule.

**Marginal Utility Schedule**

The marginal utility schedule shows the additional utility or satisfaction a consumer gains from consuming each additional unit of a commodity. It helps us understand how the consumer's preferences and choices change as they consume more of the commodity.

Let's take an example of a consumer buying apples and analyze their marginal utility schedule:

**Table: Marginal Utility Schedule for Apples**

| Units of Apples | Total Utility (Utils) | Marginal Utility (Utils) |
|-----------------|----------------------|-------------------------|
| 1 | 10 | - |
| 2 | 18 | 8 |
| 3 | 24 | 6 |
| 4 | 28 | 4 |
| 5 | 30 | 2 |
| 6 | 30 | 0 |

**Explanation**

1. **Diminishing Marginal Utility:** The marginal utility of each additional unit of a commodity tends to diminish. In our example, we can observe that the marginal utility decreases as the consumer consumes more apples. Initially, the consumer experiences a high marginal utility, but it gradually decreases.

2. **Equilibrium Position:** The consumer reaches equilibrium when the marginal utility derived from the last unit consumed is equal to the price they pay for that unit. In other words, the consumer is indifferent between consuming one more unit or keeping their money.

In our example, let's assume the price of each apple is $2. Based on the marginal utility schedule, the consumer reaches equilibrium at the consumption of 4 apples:

- When the consumer consumes 3 apples, the marginal utility is 6 utils.
- When the consumer consumes 4 apples, the marginal utility is 4 utils.
- The consumer is willing to pay $2 for the marginal utility of 4 utils, which is equal to the price of the apple.

Therefore, the consumer reaches equilibrium by consuming 4 apples, where the marginal utility equals the price of the apple.

**Conclusion**

In summary, a consumer reaches equilibrium when the marginal utility derived from consuming the last unit of a commodity is equal to the price of that unit. The marginal utility schedule helps us understand how the consumer's satisfaction changes with each additional unit consumed. By analyzing the marginal utility and comparing it to the price, the consumer can determine the quantity to consume in order to maximize their satisfaction or utility.