To calculate the mean height of all the students, including the outlier, we follow these steps:

Steps to Calculate the Mean

1. List all the heights:

   • 164, 175, 126, 135, 159, 143, 55

2. Calculate the sum of all the heights:

$164 + 175 + 126 + 135 + 159 + 143 + 55$

3. Count the total number of heights:

   • There are 7 heights in total.

4. Calculate the mean:

$\text{Mean} = \frac{\text{Sum of all heights}}{\text{Number of heights}}$

Let's calculate the sum and then the mean.

$\text{Sum} = 164 + 175 + 126 + 135 + 159 + 143 + 55 = 957$

$\text{Mean} = \frac{957}{7} \approx 136.71 \, \text{cm}$

Result

The mean height of the students, including the outlier (55 cm), is 136.71 cm.

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Would you like more details on this calculation or have any other questions?

Here are some related questions you might find interesting:

1. What is the impact of an outlier on the mean?
2. How does the mean change if the outlier is excluded?
3. What is the median height of the students?
4. What is the range of the heights?
5. How do you calculate the standard deviation for this set of data?

Tip: The mean can be significantly affected by outliers, which can skew the average and provide a misleading sense of the typical value in a dataset.