Jack was training for a swimming competition. On Day 1 of his training, he swam 400 m. On Day 2, he swam 1.1 km more than Day 1. For each subsequent training session, he swam a distance of 1.1 km more than the previous training session.
- On Day 5 of his training session, how far did he swim? Give your answer in km.
- On which day did he swim a distance of 7 km?
(a)
1000 m = 1 km
400 m = 0.4 km
Pattern for the distance swam
Day 1: ((1 - 1) x 1.1) + 0.4 = 0.4
Day 2: ((2 - 1) x 1.1) + 0.4 = 1.5
Day 3: ((3 - 1) x 1.1) + 0.4 = 2.6
Formula
Distance swam = ((Number of day - 1) x 1.1) + 0.4
Distance swam on Day 5
= [(5 - 1) x 1.1] + 0.4
= 4 x 1.1 + 0.4
= 4.4 + 0.4
= 4.8 km
(b)
Number of days he swam 7 km
= [(7 - 0.4) ÷ 1.1] + 1
= 6.6 ÷ 1.1 + 1
= 6 + 1
= 7
Answer(s): (a) 4.8 km; (b) 7