An edge of a variable cube is increasing at the rate of 10cm/sec. How fast the volume of the cube is increasing when the edge is 5cm long?

Explanation

To solve the problem step by step, we will follow these calculations:

### Step 1: Understand the problem
We need to find how fast the volume of a cube is increasing when the edge length of the cube is 5 cm, given that the edge is increasing at a rate of 10 cm/sec.

### Step 2: Define the variables
Let:
- \( a \) = length of an edge of the cube (in cm)
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