When McDonald's Corp. reduced the price of its Big Mac by 75% if customers also purchased french fries and a soft drink, The Wall Street Journal reported that the company was hoping the novel promotion would revive its US sales growth. It didn't. Within two weeks sales had fallen. Using the game theory, what disrupted McDonald's plans?

To analyze this situation using game theory, we need to consider the actions and strategies of different players involved. In this case, the players are McDonald's and its customers.

First, let's define the strategies:

1. McDonald's Strategy: McDonald's reduced the price of the Big Mac by 75% but required customers to also purchase french fries and a soft drink to get the discounted price. This strategy was intended to revive their US sales growth.

2. Customer Strategy: The customers had the option to either accept or reject McDonald's offer.

Now, let's consider the possible outcomes:

1. McDonald's Success: If a significant number of customers accepted the promotion and purchased the required items, McDonald's could achieve its goal of reviving US sales growth.

2. McDonald's Failure: If customers rejected the promotion or sales did not increase as expected, McDonald's would not achieve its goal.

To analyze the situation from a game theory perspective, we can create a simplified game matrix:

```
| Accept promotion | Reject promotion |
-----------------------------------------------------
Accept offer | McDonald's Success| McDonald's Failure|
-----------------------------------------------------
Reject offer| McDonald's Failure| McDonald's Failure|
```

In this matrix, both McDonald's and the customers have an interest in maximizing their own gains. However, the outcome depends on the actions of both parties.

Based on the reported information, it seems that the promotion did not achieve its intended goal. One possible explanation for this outcome could be the customers' response to the promotion. They may have rejected the offer despite the reduced price because they did not want to be forced to buy additional items.

Therefore, the disruption to McDonald's plans can be attributed to customer preferences and behavior. Game theory helps in understanding the interaction between players, but it cannot predict the exact outcome in every scenario. Human decision-making and market dynamics play a crucial role in determining the success or failure of business strategies.