Suppose the age that children learn to walk is normally distributed with mean 12 months and standard deviation 1.3 month. 17 randomly selected people were asked what age they learned to walk. Round all answers to 4 decimal places where possible. For the 17 people, find the probability that the average age that they learned to walk is between 11 and 13 months old.

Step 1 ：Given that the age children learn to walk is normally distributed with a mean of 12 months and a standard deviation of 1.3 months. We are asked to find the probability that the average age that 17 randomly selected people learned to walk is between 11 and 13 months old.

Step 2 ：This is a problem of normal distribution. We can use the z-score formula to standardize the values and then use the standard normal distribution to find the probability.

Step 3 ：The z-score formula is: \(z = \frac{X - \mu}{\sigma / \sqrt{n}}\), where X is the value we are standardizing, \(\mu\) is the mean, \(\sigma\) is the standard deviation, and n is the number of observations.

Step 4 ：We need to find two z-scores, one for X = 11 and one for X = 13. Then we can find the probability that the z-score is between these two values.

Step 5 ：Calculating the z-scores, we get \(z1 = -3.1716\) and \(z2 = 3.1716\).

Step 6 ：Using the standard normal distribution, we find the probability that the z-score is between these two values to be approximately 0.9985.

Step 7 ：Thus, the probability that the average age that 17 people learned to walk is between 11 and 13 months old is approximately \(\boxed{0.9985}\). This means that there is a very high chance that the average age will fall within this range.