To find the mean (average) of a set of numbers, you sum all the numbers and then divide by the total count of the numbers.

Given the numbers:
1.2, 1.4, 1.5, 1.7, and 2.

1. Sum the numbers:
   $1.2 + 1.4 + 1.5 + 1.7 + 2 = 7.8$

2. Count the numbers:
   There are 5 numbers.

3. Calculate the mean:
   $\frac{7.8}{5} = 1.56$

Thus, the mean is 1.56.

Do you want details on how to calculate the mean or have any questions?

Here are 5 related questions you might find useful:

1. How do you calculate the median of a set of numbers?
2. What is the difference between the mean and the median?
3. How do you calculate the mode in a set of numbers?
4. Can the mean be affected by extreme values (outliers)?
5. How would you find the mean of a set of numbers including decimals and fractions?

Tip: The mean is sensitive to outliers, so a few very large or small numbers can skew the result significantly.