A certain characteristic in a large population has a distribution that is…

A certain characteristic in a large population has a distribution that is symmetric about the mean m. 80 percent of the distribution lies within one standard deviation d of the mean. If the shelf’s average life is 8.6 years and the standard deviation is 3.4 years, what percent of the distribution has more than 12.0 years as a shelf’s average life?

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 #15866