Ideal timeline of the dance routine = 4 minutes = 4 × 60 seconds = 240 seconds
Variation allowed in the dance routine timeline = +- 5 seconds
Let the timeline of the dance routine be T
⇒ 240 seconds - 5 seconds < T < 240 seconds + 5 seconds
⇒ 235 seconds < T < 245 seconds
⇒ minutes < T <
minutes
⇒ 3.92 minutes < T < 4.08 minutes
So the least possible time of the dance routine can be 3.92 minutes (or 235 seconds) and the greatest possible time of the dance routine can be 4.08 minutes (or 245 seconds)