A pendulum swings through an arc length of 1120 cm (Swing #1). With each further swing, the arc length is reduced by 15 %

Question

State the growth factor.

Calculate the length of the arc in swing #5

I think im supposed to use this formula again, but I don't know how to use it. Tn = ar^n-1

Answer 1

They cagily disguise the growth factor r as a percentage. You need to convert 15% reduction to a scale factor: 85% or 0.85

So, Tn = 1120 * .85^(n-1)