I triple checked my work and I still got 0.20 m and it was still wrong.?

Part A A 116 g ball is tied to a string. It is pulled to an angle of 4.8 0 and released to swing as a pendulum. A student with a stopwatch finds that 18 oscillations take 20 s . How long is the string? You may want to review (Pages 405 - 407) . Express your answer to two significant figures and include the appropriate units. HA d ? L = 0.20 m Submit Previous Answers Request Answer X Incorrect; Try Again; 5 attempts remaining