A cyclist noted her odometer, which shows the total distance covered so far, at the end of each day of a five-day tour: Day 1: 48 km, Day 2: 110 km, Day 3: 145 km, Day 4: 226 km, Day 5: 268 km. On which day did she cycle the greatest distance, and how far was it?

The readings are running totals, so a single day's ride is the difference between two consecutive readings: 48, 62, 35, 81 and 42 km. The greatest is 81 km, on Day 4. Day 5 carries the largest reading, 268 km, but that is the whole tour rather than one day's ride — a running total always climbs, so its biggest entry is simply its last one. The figure 226 km is the total at the end of Day 4, not the distance covered on it.