Ben was training for a swimming competition. On Day 1 of his training, he swam 800 m. On Day 2, he swam 0.7 km more than Day 1. For each subsequent training session, he swam a distance of 0.7 km more than the previous training session.
- On Day 10 of his training session, how far did he swim? Give your answer in km.
- On which day did he swim a distance of 5 km?
(a)
1000 m = 1 km
800 m = 0.8 km
Pattern for the distance swam
Day 1: ((1 - 1) x 0.7) + 0.8 = 0.8
Day 2: ((2 - 1) x 0.7) + 0.8 = 1.5
Day 3: ((3 - 1) x 0.7) + 0.8 = 2.2
Formula
Distance swam = ((Number of day - 1) x 0.7) + 0.8
Distance swam on Day 10
= [(10 - 1) x 0.7] + 0.8
= 9 x 0.7 + 0.8
= 6.3 + 0.8
= 7.1 km
(b)
Number of days he swam 5 km
= [(5 - 0.8) ÷ 0.7] + 1
= 4.2 ÷ 0.7 + 1
= 6 + 1
= 7
Answer(s): (a) 7.1 km; (b) 7