Grades 9-10 Video Solutions 2021-video 2021 9-10/11

Video Transcription

Video Summary

Tom had 10 identical sparklers, each burning completely in two minutes. He lights each subsequent sparkler when only one-tenth of the previous one remains. This means each sparkler burns nine-tenths of its length before the next is lit. Each nine-tenths burn lasts 1.8 minutes (calculated as 9/10 of 2 minutes). After lighting all 10 sparklers successively, the remaining one-tenth of the last sparkler burns in 0.2 minutes. Therefore, the total burn time is 18.2 minutes, which translates to 18 minutes and 12 seconds. The total time for all sparklers to burn is 18 minutes and 12 seconds.

Keywords

sparklers

burn time

lighting sequence

total duration

calculation