Suppose that multi-level square pulses are used in a digital transmission system, and the maximum pulse amplitude is 1.1V. Suppose that the amplitude of the additive noise is uniformly distributed between (0.1V, +0.2V). What is the maximum number of levels of pulses this transmission system can use before the noise may start introducing errors? Justify your answer.

My solution is as follows:

0.1+0.2 = 0.3 V

If two adjacent signals are separated by more than 0.3 V then the noise may start to introduce errors. The maximum range that the signal can span is (+1.1)-(-1.1) = 2.2 V

Thus, the maximum levels is 2.2/0.3 => 7.33 => 7

My main question is, do I add 1 onto 7 in this scenario for the answer to be 8? Or is 7 the answer?