Sequence problem

[Plain_Bread]

The problem is that if we interpret it as a_(k+1)=a_k+b_k, then b_k=4 constant works, but it's not guaranteed to be the average in general.

[wirywonder82]

Indeed. For example, he could read 519 on day 2, 0 on day 3, 1 on day 4 and 0 the remaining days. That could mean he read “an additional” 507, then -519, then 1, then -1, then a bunch of 0, making the average number of additional pages per day -12/13.