Question

While training for a race, a runner increases her distance by 10% each day. If she runs 2km on the first day, what will her total distance for 26 days of training?

Answer 1

42

Answer 2

2* (1 +1.1 + 1.1^2+ 1.1^3 +....1.1^25
geometric series with r = 1.1, n=26, a = 1
2 [ar^0 + ar^1 + ar^2 .. + a r^(n-1)]
=2 [ (r^n -1) / (r-1) ]
=2 [ (10.9)/(.1)]
=218km