The problem is in Gujarati, and based on my understanding of the text and numbers provided, it seems to be asking you to find the value of $x$ in a sequence:

Sequence:
16, 15, 17, 16, 15, $x$, 19.

Condition:
The average of the first five numbers is given as 15, and you are asked to find the value of $x$ based on this information.

Step-by-Step Solution:

1. Find the sum of the first five numbers:
   The first five numbers are: 16, 15, 17, 16, and 15.
   Sum of these numbers = $16 + 15 + 17 + 16 + 15 = 79$.

2. Calculate the total average:
   The average of these five numbers is already given as 15. This can be verified by dividing the sum of these numbers by 5:
   $\frac{79}{5} = 15.8$ So the actual average is approximately 15.8, not exactly 15.

3. Interpretation of the Condition:
   The question might be indirectly suggesting a value of $x$ that would balance the sequence's overall pattern or smooth it out. This would require analyzing the overall relationship between $x$ and other numbers.

If you have any follow-up questions or need additional details, feel free to ask!

Here are 5 related questions you can explore:

1. What is the importance of arithmetic mean in sequences like this?
2. Can we determine other values in sequences by solving averages?
3. How do deviations from the mean affect sequences?
4. Can we establish a general formula to solve for unknown values in similar problems?
5. How does the sequence pattern help in determining missing values?

Tip:

When dealing with average-related problems, always ensure the sum of values aligns with the given average before proceeding with other assumptions.