The problem presents a series of figures, each containing four numbers arranged in an "X" shape, with the center number seemingly derived from a relationship among the surrounding numbers. To find the missing central number in the third figure, let's analyze the pattern in the previous figures.

Analysis of the Patterns

1. First Figure:

   • Surrounding numbers: $3, 9, 5, 81$
   • Center number: $7$
   • Possible pattern: One possible pattern is the average or arithmetic mean of the surrounding numbers. Another possibility is a relationship based on multiplication or division of pairs.

2. Second Figure:

   • Surrounding numbers: $2, 8, 6, 64$
   • Center number: $4$
   • Here, it seems the central number could be related to factors or some transformation of the surrounding numbers.

3. Third Figure (the one with the missing central number):

   • Surrounding numbers: $4, 7, 5, 49$
   • Central number is missing, denoted by $?$.

Pattern Recognition

The central number might represent:

• A function of products or ratios between numbers opposite each other.
• The square root or mean of certain combinations of surrounding numbers.

In the first figure:

• $7$ could be derived as an intermediary value, balancing relationships in some way.

In the second figure:

• $4$ might come from a similar logic, but it's challenging to finalize without exploring deeper steps