Question

A pendulum's first swing has an arc of 36 inches. As the pendulum swings back and forth, the arc length for each successive swing is 95% of the previous swing. If this pattern continues, at which swing of the pendulum will the length of the arc be less than 27 inches? A. 5th B. 6th C. 7th D. 9th

Answer 1

7th

Explanation:

Given :

Arc length on first swing = 36 inches

After successive swing, arc length decreases by 95%

Length on 2nd swing = 0.95 * 36 = 34.2

Length on 3rd swing = 0.95 * 34.2 = 32. 49

Length on 4th swing = 0.95 * 32.49 = 30.8085

Length on 5th swing = 0.95 * 30.8085 = 29.268075

Length on 6th swing = 0.95 * 29.268075 = 27.80467125

Length on 7th swing = 0.95 * 27.80467125 = 26.4144376875

26.4144376875 < 27

Hence, length falls below 27 on 7th swing