1.1. A coin is tossed and a dice is rolled. 9.1.2. Represent the above scenario in a tree diagram. 9.1.3. How many different possible outcomes are there?

The mean is calculated by summing all the values and dividing by the total number of values.

$$\text{Mean} = \frac{\sum \text{heights}}{\text{number of learners}}$$

The heights are $132, 132, 141, 142, 155, 156, 161, 162, 163, 169, 170, 172$ cm.

$$\sum \text{heights} = 132 + 132 + 141 + 142 + 155 + 156 + 161 + 162 + 163 + 169 + 170 + 172 = 1855 \text{ cm}$$

There are 12 learners.

$$\text{Mean} = \frac{1855}{12} \approx 154.5833 \text{ cm}$$

Rounding to two decimal places, the mean height is 154.58 cm.

The mean of the height of the 12 learners is $\boxed{\text{154.58 cm}}$.