Why acceleration is not 9.8m/s^2?

[cmkc109]

Homework Statement

An object is dropped from ret from a height of 39.4m. What is its average acceleration (assumed to be constant) if it hits the ground with a speed of 1.61m/s?

Homework Equations

The Attempt at a Solution

I actually got the answer from this question. But I am wondering why a is not -9.8m/s^2
The answer is 3.29×10-2 m/s^2, shouldn't it be negative as acceleration is acting downwards?

 

[mfb]

Possible reasons:
- The object is not dropped on earth, but somewhere else
- Some other force acts on it

The sign of the acceleration is arbitrary and depends on the coordinate system.