Arithmetic mean and standard deviation of a certain normal distribution are 13.5…

Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 2.5. What value is exactly 2 standard deviations less than the mean?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #48755