Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: if the mean of numbers 28, x, 42, 78 and 104 is 62, then what is the mean of 128, 255, 280, 511, 1023 and x ?
Options: a. 395, b. 375.8, c. 355, d. 415, e. 365
b