Grades 3-4 Video Solutions 2023-2023_3-4

Video Transcription

Problem number 5. A light engineer in the theater turns the lights on and off. She uses the plan shown. How long in total are exactly two of the lights on at the same time?  This diagram is split into minutes, so this is the first minute from 0 to 1, this is the second minute, and so on.  We need to look at each of these intervals and see in which one there are exactly two lights on. So starting here from 0 to 1, or in the first minute, there's only one light on.  But in this minute, there are two lights on. So here's one. In the next one, all three lights are on, so that's not one that we're counting. Then we have two lights on again.  And here we also have the same two lights.  In the following minute, the orange light stays on. The green isn't on, but the blue is on, so that's two. Next one, there are two lights on. Then we have all three lights on.  In this minute, again we have two lights on. Then just one.  And then we have two here, and two in the final minute. So counting how many intervals that is, we have 1, 2, 3, 4, 5, 6, 7, 8.  Eight intervals, or eight minutes, that exactly two lights were on at the same time.

Video Summary

The problem involves determining the total duration during which exactly two theater lights are on simultaneously. The given minute-by-minute analysis shows periods where different numbers of lights are on. The key intervals, where exactly two lights are on, have been identified consistently across the timeline. By counting these specified intervals, it is concluded that exactly two theater lights are on for a total of eight minutes.

Keywords

theater lights

duration

simultaneously

intervals

analysis