Normally one considers #365# days in a year or #365xx24=8760# hours in a year

and hence in #34.5# years we have #34.5xx8760=302220# hours.

However, it is well known that there are about #6# hours more every year, due to which one full day is added every four years in the leap year but again every #100^(th)# year is not a leap year as in fact a year has somewhat less than #365# days and #6# hours.

In fact the year has #5.81277# hours more than #8760# hours stated above i.e, #8765.81277# hours

Hence, in #34.5# years we have #34.5xx8765.81277=302420.54# hours approximately.