Fix a wrong translation, which also got the math wrong

[frankdu]

The original content was:

"Consider an example: a 5-second sound at a sampling rate of 16,000 Hz will be represented as a series of 80,000 values, while the same 5-second sound at a sampling rate of 8,000 Hz will be represented as a series of 40,000 values"

The Chinese translation was wrong because:

1. Incomplete translation.
2. It got the math wrong, because at 16KHz, the math is 80K data points, but not 40k.

The proposed fix is to provide full translation + get the math in shape.