A hint to get started
Combine a capped geometric plan with arithmetic increments
A student with a knee problem plans swimming and jogging to prepare for a 2.4 km NAPFA run. On day 1 he jogs m and swims m. From day 2, jogging rises by of the previous day’s distance but is capped at m per day; swimming increases by m each day. Find the combined distance after 20 days, and the first day his combined daily distance reaches km.
[2012/PJC/Promo/8]
CJC · Discussion · Question 17
Separate the uncapped first four jogs from the later fixed distance.