Number of lessons, rounding up or down?

[infinityandbeyond]

For the question attached below in a) iii), the answer from 2 sources is the 30th lesson. Like me, both get n=29.57... but wouldn't we say during the 29th lesson because the 50th hour is completed in the middle of the 29th lesson? Why do the sources say during the 30th lesson? Would that be considered correct? If yes, why?

Thanks in advance.

[RuiAce]

The 1st lesson actually covers the values \(n=0\) to \(n=1\).

Similarly,
The 2nd lesson covers the values from \(n=1\) to \(n=2\).
The 3rd lesson covers the values from \(n=2\) to \(n=3\).
The 4th lesson covers the values from \(n=3\) to \(n=4\).
...
The thirtieth lesson covers the values from \(n=29\) to \(n=30\).

The pattern demonstrates that if we have a decimal value, rounding up is the appropriate decision here.