If the mean of numbers 12, x, 42, 78 and 104 is…

If the mean of numbers 12, x, 42, 78 and 104 is 62, then what is the mean of 128, 255, 511, 1023 and x?

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 #24721