Convert Decimal 2.9: Finding All Equivalent Representations

To convert the decimal $2.9$ to a mixed number, follow these steps:

• Step 1: Identify the whole number part. Here, the whole number is $2$.
• Step 2: Convert the decimal part to a fraction. The decimal part of $2.9$ is 0.9, which can be written as $\frac{9}{10}$ since the digit 9 is in the tenths place.
• Step 3: Combine the whole number and the fraction to form the mixed number.

Therefore, the decimal $2.9$ can be expressed as the mixed number $\mathbf{2\frac{9}{10}}$.

The correct choice from the given options is: $2\frac{9}{10}$.